You only need to hook up 3 wires, so that part isn't bad. My biggest problem was that I spliced into the wrong wire twice. Then I realized that the instructions I was using were meant for an 04+ GP which has a different wiring harness than 97-03. Derp.
After finding the correct wire, programming the unit was frustrating. You're watching for various flashing lights as you go through the steps and if you make a mistake, you have to start over from the beginning. I almost rage quit a couple times, but eventually I got it programmed the way I wanted.
I was looking around for a write-up on installing it, but couldn't find one GP-specific. Since my interior is still in pieces, I may make one with some pictures for those like me that get a bit overwhelmed with the clusterf*ck of wires in there.