At the main menu, select "Options", "Cheats", "Enter New Cheat", then enter one of the following codes to unlock the corresponding cheat option:

Performance Mode - Press Yellow(2), Blue, Red, Blue, Green, Red(2).
Hyperspeed - Press Green, Blue, Red, Yellow(2), Red, Green(2).
Auto Kick - Press Yellow, Green, Red, Blue(4), Red.
Unlock Quickplay - Press Blue, Blue, Red, Green(2), Blue(2), Yellow.
Aaron - Press Blue, Red, Yellow(5), Green.
Nick - Press Green, Red, Blue, Green, Red, Blue, Blue, Green.
Johnny Viper - Press Blue, Red, Blue(2), Yellow(3), Green.
Rina - Press Blue, Red, Green, Green, Yellow(3), Green.
Air Instruments - Press Red(2), Blue, Yellow, Green(3), Yellow.
Invisible Characters - Press Green, Red, Yellow(3), Blue(2), Green.
AT&T Ballpark - Press Yellow, Green, Red(2), Green, Blue, Red, Yellow.
Gem Color - Press Blue, Red(2), Green, Red, Green, Red, Yellow.
Flame Color - Press Green, Red, Green, Blue, Red(2), Yellow, Blue.
Star Color - Press Red(2), Yellow, Red, Blue, Red(2), Blue.
Vocal Fireball - Press Red, Green(2), Yellow, Blue, Green, Yellow, Green.
Always Slide - Press Green(2), Red(2), Yellow, Red, Yellow, Blue.
Line 6 - Press Green, Red, Yellow, Blue, Red, Yellow, Blue, Green.