It'* not great to run the car that way. Although I don't know 100% what it will do. I would idle and putt around slow w/o getting on it until you get a harness in there.
ZZP Performance sells a couple things to help you along. One is the boost control wiring and the other is a map extender. Both are a walk in the park to add. Then if you had your PCM updated to a 1996 SSEi and changed the gear ratio to the ratio in your existing transmission...you'd be rockin and rolling like any other supercharged Bonneville.
00 Regal GS: All kinds of cool stuff.