PCM Update

Hello guys, I was wondering is there anyone here who knows the exact procedure Land Rover follow when updating PCM - e.g. what checks do they carry out?

It depends why the PCM is being updated - if it's a service action, is the VIN in the affected range, is there an update available (some 'tuners' increment the software level far ahead of where it actually is to prevent it being overwritten) and are there any other required updates to other modules. the Pathfinder software does most of the above, but still requires a meatbag to press 'OK' occasionally.
If you're worried about whether your remap will be overwritten - it will (subject to the above info about software incremental markers), and almost certainly your vehicle will run better for it.