There is no other method, enabling QE/CI means making Leopard use your graphics card as hardware accelerated and for that you have to make it look as it were a real Mac card, either by:

- Installing a graphics injector kext like nvkush, nvinject, corevidia, etc.
- EFI String / DSDT mod.

Try different injectors, one at a time, make sure they are properly installed. Do not use EFI strings and injectors at the same time. Some cards are special, and need a custom NVCAP string. Also I think exchanging the DVI or VGA plugs positions could make a difference in some non standard cards.