Guitar Hero 2 question?

Question

I have Guitar Hero 2 for PS2 and I unlocked every song, but I went on YouTube and found out that they had Nine Inch Nails songs. Thes were both called custom songs. How the heck did they do this?



Proof here:
NIN-THE HAND THAT FEEDS: http://www.youtube.com/watch?v=-1vGCxuV3MU


NIN- WERE IN THIS TOGETHER: http://www.youtube.com/watch?v=5iTu2s23y2k

Answer 1

You can purchase additional songs, I dont know the details (two friends have it) but you should check out the Guitar Hero website for additional info...