From the title screen, choose 'Password'.

Password	Effect
8BF-SMCX-S8L	Stage 1.
PS0-GHRK-2FK	Stage 2.
SB0-7ZZH-J8B	Stage 3.
!W5-QFHL-1X8	Stage 4.
R!1-1SZR-ZQ4	Stage 5.
4QJ-!W3L-HNZ	Stage 6.
M9V-KMWH-N4V	Stage 7.