There is an interesting article on this subject on Jim Lea's 'lifeasabull' blogspot.
I'll try and paste it here but it may be too long (so look at lifeasabullDOTblogspotDOTc*m)
You found that cuck couple. Now you’re enjoying the benefits of being a bull, regularly fucking another man’s wife. Everyone’s happy.
Except you want more. You want to take it to another level, and push yourself up the dominance ladder while pushing him down a rung or two. One way to do that is to get him to take your cock into his mouth, even if it's just briefly.
Don’t worry. It doesn’t make you gay. In fact it makes you more of a Bull, because dominance is the essence of being the Bull. You’re taking charge and asserting your dominance over them both, by demonstrating your dominance over him.
Remember: The more dominant you are over the husband, the more submissive the wife will be to you. This is one key to the relationship! Women naturally gravitate toward the dominant male. It’s part of their intellect.
If you can persuade the husband to take your cock in his mouth (even momentarily) in front of his own wife then you’ll prove to her that you’re in charge. That’s worth gold in bedroom dollars!
But what if the cuck husband is totally straight and refuses? Don’t worry. There's a way to still make it happen, if you’re patient. Look at it as a challenge. Enjoy pushing him. There is a rush to be had from making someone do something they wouldn’t otherwise do. I have done this several times and it can be fun.
There are certain steps. First, you must proceed slowly, over several encounters. Do NOT rush it.
You will learn to use the husband’s own lust to motivate him, then use sex to reward him. Also, the wife should be involved if possible. Try to recruit her to work together as a team. She may even offer him sexual satisfaction as incentive, if he will do as you (and she) encourage him.
Contrary to what you may think, you should NOT to use any humiliation whatsoever or the result will be resentment and reluctance. Use positive feedback and encouragement during the whole plan, and get the wife into the idea. If she gets into it and her husband knows it turns her on, then he will be more willing to do it.
You will probably need to talk to the wife privately. This can be done by phone, but I find that the wife is usually most receptive to ‘experimenting’ when I have her in bed and sexual excitement is highest. If he’s present, you should send him out of the room to talk (most cucks will leave when told to).
When you have her alone, I prefer to get her very aroused before bringing up the subject, usually either during foreplay or after I have just entered her. That’s when most women are receptive to new ideas.
Ask her if she’s ever had any thoughts or fantasies about her husband sucking another cock. If she says yes, you’re off to a good start. If she says no, you need to ask her if she might think about it. She will of course ask “why”.
My response here is to interject it playfully, almost like a fun game. Try things like “Let’s see if we can get him to do it. What can it hurt?”. DO NOT make it sound like you plan to force her husband to do something against his will. Many wives won’t agree to go along with that. So keep it light and playful, like a fun project to do together.
If she doesn’t go along at this point, DROP it. Don’t push it. Just move forward with the plan without her help.
But assuming she does go along, then ask her if she would like to help you. If she’s aroused enough, she will probably say yes, even if the idea shocks her. This is the best way, because your scheme will strengthen the bond between the two of you. It gives you two a common goal, and without her realizing it, you’ve created a situation where it’s now the two of you (a team) against him (the husband).
Here’s a summary of how I do it. Remember, each step is a separate sexual encounter or sex experience.
Night one: Have him go down on her before you fuck and then have him guide your cock into her pussy using his hand.
Night two: Have him 69 with her while you fuck her
Night three: Have him use his hands and some lube to get her pussy ready, and then use his hands to get your cock erect and ready
Night four (last step): Back to a 69. Have him eat her pussy to get her ready, and then have him lick/suck the tip of your cock and then put it in her. Have him 69 with her while you fuck. Repeat this several times during the night (changing positions) and he will no longer resist sucking your cock.
I will now describe each step in more detail. But one point to remember is that each step can be a separate night, or you can combine several steps into a single night. It depends on the reaction you get, and how long your encounters last.
First, make sure the husband is close to the action. If you normally fuck the wife alone, you will need to invite the husband to watch. Don’t let him sit in a chair across the room. Get him on the bed. Let him feel the mattress bounce and see the impact of your thrusts when you hammer his wife. He needs to smell the sex and feel connected to her.
Step #1 is to go down on his wife to prepare her pussy for you, then use his hand to guide your cock into her opening. Each time you withdraw or change positions, have him use his hand to reinsert your cock into his wife.
Step #2 is up more close and personal. He will make first contact with your dick, but in a non-threatening way. There are several positions for this, but my favorite is to have the wife in the ‘doggy’ position, with her husband underneath in the ‘69’ position. In this position he will be inches away, watching your dick penetrate his wife and sliding in and out of her pussy, sexually arousing him. It’s important that his wife suck his dick some to excite him, but not to the point of orgasm. You want to keep him aroused.
The wife should encourage him to lick her pussy as she sucks him. He will be so turned on that he’ll do it. Don’t worry if he avoids your dick. The idea is to get him used to putting his mouth in close proximity, and with all of the motion it will be inevitable that he will touch the underside of your shaft occasionally. Keep this up, until you get close to your orgasm.
All three of you should explode together. Afterward, he will probably pull away. That’s okay. His tongue has probably brushed the bottom of your shaft a few times and your balls have touched his face, but all in a non-threatening way. All he did was eat his wife’s pussy, which is very non-threatening.
Step #3. Switches to using his hands. You and the wife lie side by side on the bed. Tell him to take a bottle of lube and get you both ready to fuck. He should kneel between her legs and lube her pussy with his hands and fingers. Then he must move over to you and uses the lube on your cock to get you lubed up to fuck. If possible, try and be flaccid when he does this. If you’re already hard he may try to slap a little lube on your shaft and call it done. That’s not what you want. If you’re flaccid he will need to work to get you hard. That takes longer, and results in more exposure to your cock, which is the goal. During this night, if you fuck more than once, have him go down on the wife and lick her pussy between fucks, and then use the lube on you to get you hard again before fucking.
The next time is the final step. The goal this time is to make him take your cock in his mouth. It’s very important that he view the act as preparing you to pleasure his wife, NOT as him sucking your cock. Mentally that is VERY different. There are several positions that work equally well for this but doggy works best, again with him underneath.
Tell him to start licking her pussy to get her ready. Then after a few minutes push you cock against her slit and tell him to lick your cock and get it wet too. If he refuses, the wife needs to help reinforce what you want. She can tell him that she wants him to do that. She can ask him to “do it for her”, etc. She could also suck his cock to encourage him.
If he is still hesitant, tell him to lick the tip of your cock one time or he will have to leave the room. He should agree to something that simple. Then start fucking his wife, inches away from his face. After a few minutes, pull out, push your cock toward his mouth again and tell him to taste his wife (that sounds better than suck my cock).
If he resists tell him that if he doesn’t do it he’ll have to leave the room. If he’s aroused enough and gets sufficient encouragement he should open up and take your cock in his mouth.
Once that barrier has been broken, you can take it as far as you wish. I would stress that whatever you do, it’s important that you and the wife be on the same page. Read her body language to make sure she is comfortable with it (most wives get very turned on by it). If you both get off from her husband sucking your dick, then make sure she provides the right encouragement and support. After all, he loves her. If he knows it pleases her, then he will be more likely to do it. If it is a wild turn on for her, then he’ll go even further.
I have used this technique to get totally straight cuckolds to suck on my cock before I fuck their wives. To be sure, I’m not gay at all. It’s all about demonstrating my dominance, and I LOVE the way that the wives react when they see that I can get their husband to do something they thought was impossible. If a woman watches me do that, then it makes her more likely to do anything I want, too.
It can be done if you’re smart, patient, plan your play, and play out your plan. With the right encouragement the right cuckold will do anything to see you fuck their wife. A smart bull uses that to his advantage!