How about you start off with just a simple little step this weekend. Sit your wife down and tell her what you want, but keep it in check. Don't get into the whole wish list for BJs, etc. Just tell her you want to ML a little more often and a little more enthusiastically.
For any of this to make sense to her, explain why you want that, what it means to you, and what it means when you don't get that from her. Be honest and tell her how much pain you are in and your intentions of leaving the marriage after your son is a little older. Lay it on the line without worry how she will take it. Just be totally honest and give her the chance to met your needs and fail on her own account, if she does fail, rather than assuming she will fail and not saying anything.
This would be a good start, without having to get into any cage rattling. It would be a gentle kick-off to start the ball rolling. Do you think you can do this very specific thing?
