Crap....thats what I was worried about.
As long as you can scrounge up the tools is not all that bad to do. It also takes some of the lure out of differentials. 'The web' makes it sound like you need to be some sort of witch doctor to work on diffs, and it really isn't the case. You need to be patient and measure a lot, but there's no magic. to it. You won't be messing with any shims or playing with the backlash, so its not too bad to do.
FWIW, you pretty much need to take the pinion out to get the seal set properly anyway and to take the pinion out you need to remove the carrier.
These are skills that aren't bad to have anyway. If you're out wheeling the ZJ and manage to break an axle shaft there's a good chance you'll still have a chunk left in the carrier and you'll have to do some magic pulling the carrier to get it out to swap the spare in. You really don't want the first time that you do this to be on the trail.