Press A(3), B, Y, R, Select, L, Down, Up, Down, Right. The copyright and licensing screen will appear with the level number.
Crazy Hard difficulty level
Highlight the "Level" selection on the setup screen. Press Left(2), Right(2), Down, Up, Down, Up, A, X. The "Crazy Hard" selection will appear.
Highlight the "Sound" selection on the setup screen. Press Select to stop the current song. Press various buttons to play different sounds.