I post schematics of mods, measurements points and photos how I did it All photos are in high resolution. These mods are for Asus 9600GSO/8800GS and probably for 8800GT 1GB which using the same PCB (but voltages may be different).
vGPU - 1.21V (in stress is about 1,20V)
vMEM - 1.81V
After soldering trimmers, vGPU was 1.28V and VMEM 1.90V. Of course you can use 50K/20K trimmers, but I think that 20K/10K are better. Remember about providing some cooling for L6713A chip. I put there RAM heatsink, but even with that it can get warm. I'm planning make heatsink for mosfets (they are covered by heatsink in 8800GS/8800GT on the same PCB)
You do all modifications for own risk!