I sold Kevin a track bar mount I had and he showed me what he does with them. All he does is first he cleans them up, then he welds a piece of U-shaped steel to them with holes on each side. Then it is basicaly set up for a HD Trackbar.
I spent a little time under my mom's WJ yesterday. If I remember correctly the track bar mounted above the axle on hers. To use it on an XJ I think you would have to fab up a new bracket for the axle end. Then you would need to raise your steering by using a WJ steering conversion to eliminate bump steer. I think ORGS makes all of the brackets to do the conversion.