If you're like me; with one controller and the Guitar hero guitar, you can easily get this one in the local game. Just plug in the guitar in the main menu, log in as a guest and then start 1 on 1 warzone.
Locate and approach the other player, then hit the red button on the guitar and B on your normal controller, once the battle begins just leave the guitar and keep tapping B on the controller. Rinse and repeat 10 times.
Apparently this is also doable with GH drums or any other special controller with the color buttons.