They plug into the OBDII port underneath the steering column.
I have one in each of our 2 JK's, and love them.
It makes it all easy- just don't be in a hurry the first time (or any time, really) you download updates! Mark W.
PM'ed, but to answer for information's sake:
The programmers (Superchips, Hypertech, etc.) each are a single-license unit- they will only program one vehicle each.
I keep mine in the glovebox in case I want to switch programs- Mark W.