Get at least 52 batteries and assault a cop 19 times in the insanity level,stage 2. You'll hear a chime at main menu press c-up c-down(2x) z z R L L c-down c-right FAST. You won't hear a chime this time go to level 5 get 52 batteries in stage 5 and you'll get the code. Its tricky but you'll get it after the first 10 times, don't lose patience.