I replaced my rear cover with a new one from E-bay. I wrote a story about it here: Link The guides on this site are great, and I used several of them to complete my repair.
I replaced my rear cover last night. I bought a new one on E-bay, and the Pro Toolkit and replacement clips from iFixit. Other than some cringing while removing the strongly-glued battery and soft foil antenna & cover from the rear cover, it was fairly easy. I wrote a story here: Link It isn't a full guide, but it might help.