Why would you want to do this? no clue, but it is pretty funny I guess.
Start with a red character, and Eat enough Forged Pardons to go Blue. Quickly hit a moongate to New Haven(any public moongate works fine). Then run around, the npc's will still think of you as a murderer and attack you, but they get Guardwhacked. They re-spawn pretty quickly, and get guardwhacked again. Have fun with it!