After this (successful!) upgrade yesterday I thought I'd share some helpful photos if anyone wanted to attempted the same :)
Here's what you'll need:
Step 1: underneath the stereo in the center is a small plastic piece of trim, you need to remove this to expose the screws underneath:
Step 2: remove the 2 screws:
Step 3: Pull the whole unit towards you taking care then all clips are released. Try to pull out vertically as not to bend or snap anything. You'll need to unplug a cable that goes in the back of the controls so don't pull it out too far.
Step 4: The screen is held in by the 4 screws highlighted in green, the stereo by the 2 in yellow. Remove these and pull outwards:
Step 5: Remove the plugs from the screen and CD player, then refit in reverse!:
Here's the screen in:
And the finished article, before and after:
Also here's a comparison of the old (blue) and new (colour) screen side-by-side:
I notice the colour screen has an extra input (top middle) - not certain but assuming this might be for reversing camera?