attached is a diff file and a modified ebuild for XFree86 4.2.0. Save the ati.diff file in the /files directory in the portage tree, and overwrite the .ebuild for xfree-4.2.0-r12 with the one provided.
Created attachment 4707 [details, diff] Patch for ATI Radeon 9000 Cards
Created attachment 4708 [details, diff] Modified ebuild file for ATI Radeon 9000 cards
In 4.2.1-r1.