I just finished this on my '96. Got the glass first at a Pull-n Save. All the wiring is already installed in the Jeep. They (Jeep) just used one wiring harness, for the most part.
Found another donor for the switch in the dash. I grabbed one with the fog light switch, too, but there are some with just the defogger switch. Again, all the wiring is under the dash. I think mine was taped up, but it's obvious which wires plug into the switch. It's on the left side of the steering column.
For the '96 (and maybe other years??), the relay is bright red, and it's called a smart relay. They're about $40 -$50 at the parts stores...They gave it to me for free at the Pull-n-Save when I tired to pay for it. The relay center is under the dash, slightly off center of the steering column
Put the proper amp fuse in your fuse box, and you should be set. Mine works just fine, though the bulb is burned out behind the switch to show that it's on. No biggie, I'll get to it next time the dash is out.
Good luck,
Steve