Here's the official installation instructions (PDF) as provided with the Mopar cruise control kit (part number 82209481).
They no longer make the kit, but you may be able to find some leftover new old stock, or you can source out the parts individually from eBay or
http://car-part.com.
Most 03-06 models were pre-wired for cruise control (which is covered in these instructions). If yours is, then the install will be as easy as mine is. If yours isn't, you'll need an additional wiring harness for under the hood.
These instructions cover the install in detail, and I have to say that having done it myself on my 2005 Rubicon, it's one of the easiest things I've ever done. Took me maybe 20 minutes tops.
Just wanted to share this so that these instructions aren't lost to the sands of time.