Should be pretty easy. Look online, they usually make a little pigtail wiring harness that just plugs inline with the existing wiring. They aren't very expensive. I forget if the ZJs have yellow turn signals like XJs. If they do, you need a wiring converter, if you don't go the predone harness route.
Look behind the plastic panel in the back on the drivers side. I believe that is where you need to splice into the factory wiring, but it may be there already...and you might just need the pigtail for it.