There was a mod years ago for the Guitar Hero II that allowed you do your own songs. Basically it involved a couple of computer programs to copy the game disc, use your own songs, burn it to a blank, also needing a chipped PS2. The track title would stay the same but the buttons and music would be your song. Very time-consuming.
I remember a clip of someone playing 'The Touch' which is how I found out about it. This isn't the clip I saw but it gives you an idea. And the site which tells you how to do it - scorehero.com