If you look at the dash harness, there should be some wire molds that have 3 female sockets. Some are power, some are ground. If there is a free spot, a "bullet" connector available at the auto parts store should fit (there are different sizes)
This should eliminate tapping into the harness. I believe this is how the factory powered the various options (like light group)
A copy of the wiring diagrams should be available here:

http://www.mymopar.com/index.php?pid=24

hope this helps