The best way i found is use this chaine
DVI -> [DVI TO VIDEO] -> camera video in -> DV (Firewire or USB) -> PC
I use this convertisor: http://store.apple.com/us/product/M9267G/A
I use only the camera to have an analog video input for my mac...
After in Max you can use the objet to grab a camera signal...
Good luck.