Just for those of you who can't get a boosting partner to play with, this can actually be done solo, with a little bit of fancy finger work.
Use a guitar controller for the lead, and a controller for the bass.
Start up the song 'Movin' Out' in tier 2. The guitar has enough notes and 2 star power sections before the bass comes in.
I did it on medium, but I am sure it can be done on any difficulty.
Place the controller on your leg, and place the butt of the guitar beside the controller. Then just earn the star power, and tilt the guitar at the same time as pressing select on the controller