Not as bad as you might think.
The dash comes out pretty easily and as it is all electronic it is just a couple of wiring plugs to disconnect once removed, removing it was I think four screws behind the cowling, which popped off pretty easily. Once it is out I don't think I even had to remove any screws from the dash assembly (I did it five years ago, memory is getting a bit dull) it was just a matter of very carefully levering the tabs in to pop the clear plastic panel off the cluster and then carefully glue the filter film in behind the screen printed front face of the dash without actually dissasembling anything more than that. It only took me an hour or so to do the whole job. All it needed was the filter film, the glue, a couple of screwdrivers and tweezers to slip the flim in with.
I can not recall what it is called but the glue I used is normally used to stick photos down, is rubbery, dries clear and neutral cure if you get it wrong you can still unstick it and the cured glue rubs off with your finger. I will find the tube tonight and post up what it was, or ask my wife, she is the photographer.