Debug:
Go into the Options menu. Put the cursor over DIP Switch, and hold down X, B, and Z. While holding down all three buttons, press A to access the DIP Switch menu. As soon as you press A hold down on the D-pad (without letting go of X, B, and Z). If done correctly there will be a 'debug' option toward the bottom of the list of options. Turn this mode on and you can do a bunch of cool stuff, like watch all the endings and max out your character for the story mode.

Turn the debug on, and at anytime in the story mode, pause the game. Hold down X, Y, and Z, and press up to replenish life to max, or press down to kill your character.

Thanks to Revolution readers Lefty LaRue and Jeff Hsu!