Hi Tom,
To clean the internal mirror, I just wiped it over with a clean micro-fibre cloth which attracted all of the dust. The rear mirror needed nothing doing to it. The inside of the front screen I used a microfibre cloth and some of the Mr Muscle window cleaner spray (note: do NOT use that creamy windolene stuff!) and cleaned the inside, same as for the front. My other half is a smoker, so I got a lot of crap off it, if you have no smokers in your house you may get away with just wiping it over. Don't forget to wipe the lens over as well, microfibre cloth again for this as it also had a coating of dust!
A couple of tips - you will need to remove the subwoofer to get the bottom of the screen bezel off, so do that before you start. Also when removing the screen, you need to remove the top bracket and the two side ones - just slacken the bottom one off and gradually lift the screen out, makes it much easier to re-assemble if you leave the bottom bracket attached

One last tip, be sure to hold the screen by the edges once you have cleaned it, otherwise you'll do what I did - reassemble it all, and notice some massive fingerprints in the corner
Hellraiser...............>