My buddy, a Land Rover tech, did the install for me over the weekend. I was going to do it on my own and found this DIY, but when a dealer trained tech offers to do it for you, you don't mind!
But one thing I noted (I work on my other cars quite a bit) - instead of removing the compressor from its mounting bracket (by undoing the bolts with an allen key), remove the entire assembly from the car. There are three bolts that hold the bracket in place, two on the bottom, one up top that is hidden from view. The photo in the thread with the compressor removed shows the bolts I mean. If you use a 1/4" extension with a universal joint, you can get in there to undo the top one. Beats trying to get an allen key into position with the risk of rounding if the bolt is rusty.
Then you can just swap the compressors onto the bracket on the workbench. With the bracket removed, you can also see that the holes for the bottom two bolts are circular, but the upper one is elongated - aids in re-installation as then you don't have to be spot on with the top bolt. Suggestion is to loosely install the two bottom bolts, and then you should be able to get at the top one.
My buddy advised that the trick to doing this method is to leave the upper plastic cover in place, or to reinstall it first.
My symptoms, confirmed with the diagnostic computer my friend had, was that the compressor was quite noisy, and of course the suspension fault warning light came on with 'normal mode only' flashing on the screen.
With the new compressor in place, everything was good to go again.