Press R + Down, Up, R + Right, B + Up, L + Right, A + Right, X + Right, Y + Up, A + Left, Select + Left, L + Left, Select + Down at the title screen. A chime will confirm correct entry.

Note: For each instance of two buttons needing to be pressed (R + Down), press and hold the first button, then the second, then release both. During gameplay, pause and press R + A + Select to enter the level select.