Instructions
Use the strum bar on the guitar controller to navigate to "Options" on the main menu.
Go to "Cheats" and "Enter New Cheat."
Press the appropriate color button in sequence and strum to enter a cheat code. For example, if you want to play in Hyperspeed press Orange, Blue, Orange, Yellow, Orange, Blue, Orange, Yellow. If you want to play in "Performance Mode," you'll need to press some buttons simultaneously. The sequence is Red+Yellow, Red+Blue, Red+Orange, Red+Blue, Red+Yellow, Green+Blue, Red+Yellow and Red+Blue. To activate Easy Expert Mode, press Green+Red, Green+Yellow, Yellow+Blue, Red+Blue, Blue+Orange, Red+Orange, Red+Yellow and Red+Blue.