I'm actually not sure what I would do. I would first try to figure out the reason why he will not seek help (ie. embarrassment, shame, etc.). I would then try to help him overcome that fear and see if he would get help. If he absolutely refused, then I may begin to threaten to leave, seeing if maybe that would push him to do it. I do not know if I would leave.
It is one thing to be impotent... but to refuse to please your wife in any manner, is very strange. I think there is something deeper that is affecting this marriage, and I think marriage counceling may be the first step.