You can make it an auto with junkyard parts,
The Jeep AW4 Transmissions - Novak Conversions is the auto tranny that came in that model jeep. You need the
transfer case with it, or change the input shaft on your current
transfer case to match the output of the auto.
You also need the tranny computer and related wiring, possibly the ECM and the
TPS wiring for an auto.
It's a lot of work, would be best if you picked up an auto XJ that needed parting out and could have it on hand for the swap.