If you install it in a 99 or newer it's almost a bolt in,except for a few wires in the dash harness that must be moved to work with the 2.7 engine harness.
But to put it into a 98 or older version it gets quite complicated even for a seasoned mechanic. Some of the things needed are:
2.7 engine and engine wiring harness
Exhaust manifolds and Catylitic converters
Underhood wiring harness from 2.7 donor
Dash harness from donor vehicle(must splice to work)
Radiator(Must make up custom mounts-wider than stock.
Electric fans or fan(stock fan to close to radiator)
Shortened rear driveshaft(depends on Trans. used)
Front driveshaft from XL7 with 1.25" spacer
Plus alot of little stuff,the wiring is the hardest part,i wouldn't do it again if i knew how much of a pain in the ass it would be. In a 99 or newer i would do it in a heartbeat.