MASTER CODE:
 D002A9A8 000D

Player 1 infinite lives:
 800CDF42 001E

Player 1 infinite ammo:
 800CDF3E 03E8

Player 1 infinite smarts:
 800CDF40 0003

Player 1 max power-up:
 800CDF3C 7FFF

Player 2 infinite lives:
 D004B138 0002
800CDFCA 001E

Player 2 infinite ammo:
 D004B138 0002
 800CDFC6 03E8

Player 2 infinite smarts:
 D004B138 0002
 800CDFC8 0003

Player 2 max power-up:
 D004B138 0002
 800CDFC4 7FFF

Have all keys:
 80107AC4 000F

Start on level X (Note 1):
 8004B134 000X

Note: The Infinite Health codes previously posted here only worked on level 1.

Note 1: X is in hexadecimal, i.e. for levels after 9, use letters (A=10, B=11 etc).