BAMT x64 works just fine (well it does require manually fixing it). 8 GPU are no more complex then 1-7 and simply require a x64 kernel, nothing more.
Still it is like beating a dead horse so will leave it at that.
Funny, I could have sworn that it took myself and Little Duke several days of work to make that hacked up, outdated test version of bamt x64 that a few people are using. (The same one, btw, that so many people had so many problems with that we decided not to go x64).
If only we had known that it simply required a 64 bit kernel..