Heres a guide to installing Jaywalker's OpeniBoot for iPod Touch 2g. This program is still Alpha so dont expect to much. I also prefer that you have backed up your iPod Touch and have nothing you wouldnt mind losing on it (A.K.A you might have to restore if you mess up or something) Ok so lets...
@Xdqwerty, Osu! Tatakae! Ouendan! is the Japanese version of the game, different settings/characters/songs but otherwise identical mechanics. I played that before I knew about Elite Beat Agents lol. Both fantastic games https://en.wikipedia.org/wiki/Osu!_Tatakae!_Ouendan