Anthony Hernandez (did I spell it right?), a.k.a. Nosfiratu, CL's Tech Writer is working on documentation for this. I think he has a rough draft of the document that is available if you e-mail him. Kevin Rose used to have great website that described the cr2 format, but currently is between websites as I understand it. Compose, a java-based utility available in Free Stuff here, can extract geometry from cr2's (and pz3's as well I beleive) and give you some options for materials (you can rename materials or split groups by material, etc). You can also use UV Mapper to select certain areas of your mesh and assigne them to groups or materials. Hope this helps.