I took mine out a couple of months ago - still out!
As David says, the post trims and door rubbers are the thing. There's a good video somewhere that I watched first - on one of the other forums, but accessible to non-members. It might have been landyzone... which I joined once, but left quickly because of the high proportion of (apparently) 5 year old contributors!
Anyway, the video is pretty good, and highlights leaving the rear pillar trims and clips in until last, to give you room to work; and I think fully reclining the front seats to allow the lining to lie down on top of them.
Even when it's completely loose, it's still not the easiest thing to get out of the back of the car. You'll need a fair bit of space behind the vehicle to pull it out.