I don't think these teachings apply to a man who is completely impotent. First of all, the church says nothing about the man giving the woman a handjob--it's perfectly acceptable, although not necessarily within the "spirit of the law". So that'd be okay.
As far as the fella, I'm sure exceptions would be made in that case. Our church is like any other, in that it realizes that the purpose of sex is both to create babies AND to help the people get closer to each other. To expect a couple to be celibate forever because of a physical disability is not in keeping with any of the teachings that I've ever read, and I've read a LOT of Catholic sexual teachings, for obvious reasons. Gotta stay on top of MrHP, you know.
Now if he'd only let me stay on top of him for real I'd be set........
