Changinge a whole engine is actually easier than fixing one. Go with what Assassin has said. The one hangup you will have (and the only answer is TAKE YOUR TIME) is realigning the engin to the gearbox. Bye / borrow a clutch aligning tool (put a new clutch in while your there unless the one on the enine is really good, to save taking it all out again in a years time). Sliding the clutch plate (which is bolted to the back of the engin) onto the input shaft of the gearbox is the most fidilly part of an engin swap. Take your time. Use a trolly jack to hold up the front of the gearbox. It's all about getting the angle just right. When you do it'll just slide together easy as... Don't force it. Get the angle wrong and force the bell housing bolts to do up thinking it'll all straighten out and you'll prob end up braking something and having to start again. If you get to a point where you've almost got the bell housing snug up to the engine block, but it wont quit go, the end of the input shaft is probably through the clutch plate but not in the hole in the centr of the flywheel. changing the angle of the gearbox / engine a little (in the right dirrection) will sort this. It also helps to have someone hold the clutch peddle down while doing this. Ir if your on your own keep giving it a pump after each adjust ment to angle. If the clutch is not perfectly in line it can stop the shaft going into the flywheel. Pushing the peddle down can just take enough pressure off the plate to allow it to slide a little, alowing the shaft to penitraight.

The fastest a friend and I ever did engin swap (on an F20, very simple) was half an hour. That was from first bolt undone to driving car out of workshop. All the right tools and younger fitter us helped a lot. Normally I'd expect a 4x4 engine swap to take a days work on your own. I did an engine out clutch change on my Sporti about a year back, that took me about 5 hours on my own if memory serves.