With four people this can be done on almost any song. Supposedly this can be done solo on some imported songs thanks to unison bonuses appearing in solo play, but it is far easier to do with multiple people. This can be accomplished on almost any song (obviously it needs to be 2:00 or longer), but some claim that this can be done on solo guitar on a host of songs from Rock Band 1 and some early DLC. Two people can maintain overdrive for most of the song on many imported songs though. Coordinate with your partner and make sure that they only activate overdrive when your overdrive is about to end. A drummer or vocalist should always start the overdrive chain, since they can only activate at certain points. You can find a partner in the Achievement Trading Thread here.