I think the main problem with that (apart from the fact that a lot people would think that'd be some sort of sacrilege) is that it just wouldn't mesh well. The cinematography, budget, cast all look too different for it to work in either the Reeve films or the Routh film.

I've thought about editing seasons of Smallville into lengthy 'movies' - as wmgan has done with Buffy season 6. I think that season 4 would be the easiest to do so far as it is quite cinematic in parts and you could really streamline it to be all about the search for the stones. The only thing, apart from real-life and time issues, that has kept me from attempting it is the ridiculous witch junk. Most of it could be edited out. The problem arises when you get to China, how can you edit the episode to make sense if Lana all of a sudden becomes a witch. The nice thing about season 5 I think is that it's the first season to have 5.1 sound (maybe that's only on the HD-DVD release though which has been delayed).