Before starting Comix Zone, go to the "Options" menu, then to "Jukebox". Press the button mapped to C on the following numbers in order: "14", "15", "18", "5", "13", "1", "3", "18", "15", "6". After you hear "Oh yeah!", press the button mapped to C on "3". Back out of the menu, and start the game to get the "Hardly A Hero" achievement.