At the 'Main' menu go to 'Options' and then 'Cheats' and select 'Enter New Cheat' and enter the following codes (each combination of notes must be strummed) to unlock the corresponding feature. To disable a cheat press Green at the 'Cheats' menu.
Unlock Performance Mode: Press (GR) (GR) (RO) (RB) (GR) (GR) (RO) (RB). Everything disappears except for the performance in this mode.
Unlock No Fail Mode: Press (GR) (B) (GR) (GY) (B) (GY) (RY) (O) (RY) (GY) (Y) (GY) (GR). This code cannot be used in Career mode.
Unlock Hyperspeed Mode: Press (YO) (YO) (YO) (YO) (YO) (RY) (RY) (RY) (RY) (RB) (RB) (RB) (RB) (RB) (YB) (YO) (YO). This mode will makes the charts faster. There are 5 Hyperspeed levels and to cycle through them Press Green on the Hyperspeed option at the 'Cheats' menu.