The easiest I have found was to have the tailgate down. It makes it much easier to get to everything and to see the bolts. You will want the window most of the way out, and supported when you do it.
Don't try to remove the window without removing the weatherstrip from both sides, it will damage the weatherstrip.
You can change it with the window still in the gate, but it is a bit more complicated since you must support the window once you unbolt it from the roller tracks.
There are four bolts that hold the regulator in, then it simply lifts up off the crank mechanism and the slides down out of the hole. Fairly easy to do once you get in there and see how it all lays together. Once that is out you can get to the bolts that hold the actual crank mechanism and change it out. Then reverse it all to put it back together.
When you put the new one in, make sure you rotate the crank handle until it engages in the slot on the regulator before bolting down the regulator.