Toolmonger is offering up a how-to guide for building a custom Guitar Hero controller -- using a real guitar! Be warned, it's a difficult task, as the original modders can attest. It took Toolmonger a full 75 hours of dirty work (read: deconstruction, cutting, and mangling). Thankfully, the site documented the process down to the minutest detail. Did you know that cat-5 networking cable is the ideal wire to run inside the neck?
Alternatively, you can try your luck at winning the modded guitar during "Funde Razor II," an event to raise money for Child's Play.