....but how do you get someone who sees no need to change themselves to do something?
Simply put, you can either use a Carrot or a Stick, or both simultaneously.
The Carrot
Remember ye olde Marriage Catch-22 from Michele's book? For most women, a strong emotional connection is required in order for them to feel a desire for sex. If the emotional connection is not there, it ain't happenin'. From what you've reported, your wife allegedly "despises you" and only offers up criticisms or complaints when you want to have a serious discussion with her. That says to me that the emotional connection is no longer there, and that there are a few years of anger and resentment there in its place. Since you have your own load of anger and resentment, the two of you are entrenched, and no one is actively trying to meet the other partner's needs, because your own needs are not being met. Stalemate.
The solution is to do one of Michele's 180's and start doing what you can to swallow your pride and start meeting your wife's needs, even if your own are not being met. As I said in Dance's thread, this is NOT easy to do, especially in the beginning. It feels very one-sided. However, the only person you have the power to change is yourself, so that's where you start. Luckily, the positive feedback-loop nature of marriage means that, eventually, your wife will be forced to respond positively to your positive efforts, perhaps after an initial bout of skepticism about whether you really mean it, and aren't just "trying to get laid."
You may be so discouraged, angry, and resentful yourself right now that there isn't much you're willing to do to meet her needs. That's OK: set some small, realistic goals (see the SSM section on goal setting), and start with what you can do. You may have tried some things in the past, which didn't work for whatever reason, but don't give it up -- go back over all those complaints that you've been hearing over the years, pick one area, and set about fixing it. Once you're doing that in a sustained fashion (it's become a habit), go on to another item. At some point, she'll realize that she doesn't have much of a complaints list anymore and will start to appreciate it AND look for ways to return the favor -- there's your opening.
The Stick
Both DanceQueen and NOPkins mentioned this; that is, to quietly and firmly deliver an ultimatum to the effect that the status quo is no longer acceptable, and while you are willing to make significant changes to meet her needs, she must be willing to do the same thing for you. She must understand that a marriage in which you are both miserable for the NEXT however many years will not be tolerated -- change must occur on both your parts.
Admittedly, revealing this Stick is scary as hell to do, and it has to be absolutely honest on your part -- you have to be willing to go through with it, either way. If you don't mean it, don't say it: no bluffing permitted.
I personally used both the Carrot and the Stick, but only showed the Stick after I had proven to her that I could make significant changes myself (displayed the Carrot for a couple of months). I was only able to do either after a long period of soul-searching and a decision that (1) I refused to go another 20 years or more miserable and lonely within my own marriage, but (2) I was willing to move heaven and Earth to set things right again. In other words, I decided that it was either time to fish or go cut bait.
I don't know where you are, Near, and I absolutely do not want to push you one way or the other: it's your life, your marriage, and you have to live with the consequences. If you think that you can live with the status quo, then start making some positive changes on your own and go with the Carrot only, but if you are at the end of your rope, then your wife needs to understand that as well -- she needs to know the consequences of her inaction and apathy.
Take care,
Bagheera
Me 50, W 45, M for 26 yrs S25, D23, S13, S10 20+ year SSM; recovery began Oct 2007