Stick your camera in Av mode and you're done. No AF confirm, though. As for the lenses themselves, that depends on which batch the camera comes from, etc. You can shave the mirror, or shave the lens shrouds, etc.
Bellows will have absolutely no problems, unless I have missed some lenses which extend WAY back into the bellows. Trying to hit infinity on some lenses may cause problems. (and are well documented), but I fail to remember a single case of anyone having problems at macro focusing distances on any lens. I suppose some floating element-style lenses could have problems if the rear element remains parked, but still, I don't remember a case of anyone having any issues with mounting macros.
Good luck and happy shooting,
Daniel
Oct 17, 2008 at 12:18 PM
Steve Spencer Online Upload & Sell: On
Here is a great database that should tell you about a lot of Contax/Zeiss lenses. The 5D and 5D II are likely to have similar issues, but we won't know for sure until the 5D II has been out for awhile.
Another concern may be if the bellows will clear the prism area. I use a Contax Bellows on my 5D with no problem but on some of the other EOS bodies the camera cannot properly lock onto the bellows because the prism box hits the rear of the bellows assembly.