I had chap from South West Sunroofs in Yeovil do mine. He does travel, and did mine at my house. I'd only just got the car and didn't fancy pulling the headlining down, with the inevitable busted clips etc.
However, he didn't do it that way - he removed the trims around the interior of the sunroofs and the interior lights and then used a right-angled drive attachment on his battery screwdriver to get at the screws holding the sunroofs on. Pretty neat way of doing it I thought.
If you don't fancy doing it I can recommend him. Mind you, having seen how he did it I would attempt it myself next time, although having replaced all the seals with Land Rover bagged items and put a bead of windscreen sealer stuff around the frame it shouldn't need doing again!