It's a bit tricky getting the new one on from what I've heard/ read.
Last person I know who did it was Ditch off RSOC..well I think it was him..lol. Can't find anything from him, but a couple of threads to read:
http://bbs.rsownersclub.co.uk/showth...ht=roof+lining
http://bbs.rsownersclub.co.uk/showth...ht=roof+lining