I've done that in both a YJ and an XJ. It's pretty simple. Take the manual transmission out, unbolt the flywheel, pull out the pilot bearing (don't forget this step!), bolt on your flexplate, bolt up your auto transmission, bolt your torque converter to your flexplate. Then you just plumb in a cooler, and hook up your favorite shifter. If it's a computer controlled auto transmission (like an AW4), you have to hook up the TCU, or make your own. Don't forget the kickdown cable!