Me and a buddy did my 5.13 and ARB install a few weeks ago, the actual gear set up took the better part of a day. He is an experienced gear installer too.
If you have the down time, the tools, and the desire to learn then I say go for it. Its a tedious process which involves a lot of trial and error. Precision down to the thousandth of an inch, and resistance to in/lbs. I wouldnt say it is hard, but as I mentioned, it is very tedious. Having the axle out and on a table or the jeep on a lift will make things a lot easier.
Otherwise, sub it out to a shop who knows what it takes to install gears.