To do this, you must have the ''Pushya'' ammo algorithm. Face opposite the direction you want to go, and use it repeatedly. Pushya doesn't take any offense or agility to use, so if you have it you'll never get stuck again.
While you're playing, press RS, RS, LS, A, C, B, Right, Left, LS. Then hold X and you'll open the Ultimate Cheat Menu. Keep holding X and press:
A to Increase Defense
B to Increase Offense
C to Increase Agility
LS to Toggle Invincibility
RS to Increase rank