What he said (^^^.)
Honestly, it's not that difficult to do a tuneup on a 4.0L - the engine isn't jammed in sidewise, and you can reach everything fairly easily. I've done tuneups in between classes myself, and I've done them on lunch breaks (leaving plenty of time to eat lunch.)
Unless you're going to get silly; plugs, rotor, cap, and wires takes about 15 minutes. Add 10-15 more if you're going to change the air filter and the fuel filter. Weave in another 10 minutes if you're going to change your oil as well (and you can let it drain while you're doing other things - so it would really only add about two minutes - to change the filters - and another five or so - to dump in the oil - overall.) Should easily be doable in under an hour - has been for me.