I ordered this yesterday, and have just fitted it myself, using this guide.
Even for a fumbling sausage-fingered retard like me, this was incredibly easy to do. The only thing different about mine compared with the guide is that mine had a telephone prep/bluetooth microphone attached to the light cover. The wire for this easily unclips from the light cluster, so I didn't have to drill the holes with the cover dangling from the roof!
Thanks to Tiffy for the idea, and to Bez for guidance.
I'll take a pic later, when it's dark, and show the effect.