I did mine yesterday. It took about an hour because I've never done one before. I had to take the bolt off of the bottom of the window guide rail (a 10mm bolt that is inside of the door and faces the back of the car if the door were to be shut), and the large torx bolt off that is on the back of the door (top of the door jamb area). And obviously the 3 torx bolts that actually hold the door latch in. Once the window frame was unbolted by those 2 bolts, I was able to flex the frame enough to get the lock out (It is tight, but it works). I first tried sliding the door latch down to get it out, but ended up having to slide it back up to its stock location, and rotate it out while flexing the window frame out a bit with the window up of course. Really not that bad. Just make sure you get the clear plastic vapor barrier back in correctly, you will get moisture in your car if you don't.
Here is where to get the door latch/lock assembly:
Land Rover parts and Accessories, Range Rover parts part number: FQJ102900 Price: $124.50
I got mine used from a local truck getting parted out on Craigslist for $30. May want to see what used options you have.