I asked this last year when i had the chance of a set of cheap leather seats.It would seem that the rear seats are different to the saloons,& would not fit properly.Also i think,the Estates all came with 3 proper seat belts in the rear,but the saloons only had a lap belt in the middle.
But i supose that any thing is possible .
I was also considering a leather interior from a Estate VSX however i was told that they wouldnt fit...however i do remember Wilkobob's words "Arh, we'll make them fit "