Maybe i'm too late to respond but try this.
Start over, and try this:
amdfx GraphicsEnabler=No PCIRootUID=1 -v
I was able to get through the install with those tags, just make sure under "Customize" while your drive is selected, you disable GraphicsEnabler
Then on your first boot, make sure to use "Kernel Cache"=amd GraphicsEnabler=No PCIRootUID=1 -v (mind the spaces)
On another note: I am getting really bad interference on any driver i use for Audio... distortion/clicks/pops/noise..... i actually think it may have done damage to my speakers..... i tried using a different pair, sound is still distorted with tons of noise