About once every six weeks or so, my XJ gets pressed into service to tow some random vehicle that someone I know needs to get from A to B. Since most of them tend to have been sitting for some time, this usually means towing them on a flat trailer. From my experience, here's what I can tell you about towing with a Cherokee:
1) You'll go through brakes rather rapidly depending on how often you're towing and the weight of the load.
2) The 9" discs up front get hot really quickly with a heavy load on the back. This coupled with 1) above means that a braked trailer (electric, surge, or otherwise) is pretty much a necessity.
3) Both 1) and 2) above mean using engine braking wherever possible on more-than-moderate inclines. With that in mind:
4) Fit an oversized auxiliary transmission cooler and make sure that your cooling system is in good shape beforehand if you're going to do this on anything approaching a regular basis. Also make sure that your gearing matches the size of your tyres if you're not running a stock setup.
5) Don't go over 60mph. Most state laws limit vehicles towing trailers to somewhere in the region of 50-55mph, but keeping everything in mind above, exceeding that number is likely not going to be beneficial to your XJ's longevity.
And finally:
6) When towing with a Cherokee, BE AWARE OF WHAT'S GOING ON AROUND YOU. An XJ is like an ant: it'll move a surprising amount of weight for its size. But the problem is that is doesn't necessarily have the mass or dimensions to cope with the weight that it's toting as well as a larger vehicle would. Keep to the right lane whenever possible, remain alert for idiots, and plan ahead as much as you can. If there's one lesson that's been impressed upon me from from dragging stuff around through idiot Los Angeles drivers, this is it.