Not sure if this warrants its own thread or not, and this applies to the PS2 version I think. Anyway a friend of mine is a hardcore fan of the GH series and I play some too. He is currently working on modding his PS2 to play custom songs. Some videos of random songs are
here . I'm sure you could find instructions on how to attempt the whole process with google, my friend said it wast too complicated. We are going to be really excited if this works out.
Just thought I'd bring this to the attention of anyone who always wished they could play Metallica or Dragonforce or something. Because you can with a little work.
EDIT: Don't know if this has been brought up or not and if it has, apologies. Also, if this is not cool to mention mods feel free to delete it.