Mission select
At the mission selection screen, click Left Analog-stick, press Black, R, click Right Analog-stick, White, L.

Mission skip
While playing a mission, click Left Analog-stick, press White(2), Back, click Right Analog-stick, White.

Alternate music
At the front-end, click Left Analog-stick(2), Right Analog-stick(2), press L, R.

Joke mission briefing
At the armoury screen before launching missions 1, 3, 6, 8, 9, or 14, press L(2), R(2), click Left Analog-stick, Right Analog-stick.

Change Music
To change the music, do this at the title screen: click the Left analog twice, then click the Right analog twice, then press L, R.

Cheat Mode
During mission select press Left Anolog stick,black,black,R,Right anolog stick,white,L

Finish Current Mission
During gameplay press Left Stick,white,white,black,right stick,white.