I have a 7600GS running ok.
I Use NVINJECT 0.2.1 from iPC but I got 512MB and no QE/CI like you.

This worked for me:
Modify the file /system/library/extensions/nvinject.kext/Contents/Info.plist
Edit it and find this:

<key>VRAM,totalsize</key>
<data>
AAAAIA==

Replace the I for an E : which means to change 512 for 256MB

It should look:
<key>VRAM,totalsize</key>
<data>
AAAAEA==

Voila!! I get 256, and QE/CI running.
I hope it helps, let me know.
Regards
Dragon