hi there silentmac, i use 10.5.2 rev 1(cant get rev 2 to run,waiting for root). i did the install as normal, selected customize and selected x1600 kext although on rev 1 i dont think these get applied correctly. upon first boot i get error about kexts not installed correctly, at this point i do all software updates including graphics update 1.0 (if software update doesnt offer this get it from mac update site and install) restart. at this point i copy any kexts that were complained about (ie sound card usually) to the desktop and reinstall them using kext helper. then i copy 3 kexts that i hex edited for my card atinject, atindrv (make sure ATY_Wormy.kext is in plugins folder), ATIRadeonX1000.kext install using kext helper, reboot viola QE/CI res change (i use 1900 x 1200). others have tried using my kexts but resulted in kernal panics. this works for me i have done many reinstalls using the method above and works every time..sorry for the long diatrob.

hope this helps

Firewalk