I did mine myself.
Would recomend getting someone that knows what they are doing to have a go though.
What i did
Ran audio/picture cable from headset behind glove box.Up passanger pillar and across roof to centre light.
Coat hanger if handiest to use to grab cable from top of pillar rather than trying to remove roof lining.(nightmare to get back on easy to get off)
I removed rear/middle interior light and wired in screen.
What i did wrong.
Didnt put breker/switch from live wire of interior light.
You can turn on/off screen with switch but there is still power going to it all the time.
Some mornings there is no condensation on a small circle on the roof where the screen is
Also if the wire from headst is not connected properly you have to take down and reconnect and re fit. Base plate is a knightmare and sore kneck guaranteed
In saying that works perfectally and keeps them happy.
So if anyone wants to have a quick look at mine as I know duck all about currents etc and would like to have a second opinion.Im sure its only something small that i missed
In saying that seen a nice set of twin screens in cash convertors the other day(joys of working bank holiday) for 69.00yo-yo.