Not joy2key, haha, xpadder is alot better, you can download images and just press the button and it picks up, then assign to the F1-F5 keys (or whatever is you frets) i agree. i have XPadder; I used to have Joy2Key, but it only worked for my Guitar Hero III guitar. I'm working on XPadder right now....
If you plug it in while running Joy2Key (google it if you need to download it), you can go to settings, key settings, and press each button for the corrosponding note.
i JUST figured out how to do it like 2 hours ago, so yeah