I found a cool website which has a lot of backing tracks of many songs, some of them have everything except vocals/lead/rhythm and most have vocals but not lead or rhythm.

I think it would be nice to play a cdlc where you only hear your guitar play the part instead of the songs guitars.

http://www.guitarbackingtrack.com

Search 'multitracks' in Ignition. Boom. (I can also whore out my tutorial, why not: http://customsforge.com/topic/16707-how-to-create-customs-with-multitracks/ )

 

It's also worth noting that the FAQ on that site you linked states 'The tracks are made in many ways, ranging from beefed-up MIDI files to manual recording of every instrument. The quality will of course vary, but hey, it's all free!' so they might not be entirely accurate in sound or tempo. I hadn't poked around on it much, but just a caveat.