Homebrew Picodrive and Zombies ate my neighbors.

[inovermyheadd]

I got this rom to work on my M3simply but I can't switch weapons b/c I guess the key isn't there that allows you do to so. I tried to change the controls in the game options but after you switch player one's controls it prompts you to change player 2's controls. The problem there is that you don't have control over player two. Anyone have any suggestions?