At the Warning screen (the one telling you the implications of Skitchin' in real life) press the following combination:
B, A, Down, A, Start, Start.
This will allow you to enter special codes at the Password screen.
On the warning screen press B, A, Down, A, Start, StartOn the main menu select password with eith the A,B or C button, but not with StartAfter typing in the password, use the Start button to confirm