Ps3 guitar hero controller on the PC flavor of GH

 

-Download Joy2Key (http://www.oneswitch.org.uk/2/I/JoyToKey/JoyToKey.htm)

-Download this config file (http://davieslim.googlepages.com/PS3Guitar.cfg)

“- extract the JoyToKey file and throw in the PS3 Guitar config file into the same folder where you extracted JoyToKey.
- Plug in the Guitar’s USB connector.
- Run JoyToKey and choose PS3 guitar.
- Run Guitar Hero 3/Aerosmith for the PC. (should work for Frets on Fire)
- Go to Options > Controller > Configure Keyboard and set it up this way

Green  —– 1
Red     —– 2
Yellow —– 3 
Blue    —– 4
Orange —– 5
Star Power —– 6
Whammy —– 7
Mouse Whammy —– X-Axis
Strum Up —– Button 1
Strum Down —– Button 0
”

Source: http://davieslim.wordpress.com/2008/11/02/using-ps3-guitar-hero-controller-on-the-pc/