The only discrete channel versions that have been released are the special editions, and of course they have a lot of extra sound effects that were not part of the original version. I'm not entirely clear what's being asked here—taking a mono version and combining it with the surround channels from another recording? I guess it's possible, but I don't imagine it would come out sounding that great. I've been asked before whether the dialogue of my 5.1 can be replaced with an alternate language, but I am obliged to state with certainty that this will not work, due to the impossibility of isolating the speech from the rest of the mix. I don't think the LFE can be used with a different recording, either, seeing how I've had to level-match it very precisely to the dynamics of the 1993 mix, and if attached to another version it would almost certainly seem as though it had been tacked on, rather than integrating smoothly into the total sound.
Anyway . . . it's nearly done, guys. It's really, really close. In fact it would have been done already, if I weren't painstakingly trying to identify and solve phasing errors. I've already gone back on my previously stated position of not using the 1993 mix as a source for the LFE channel—I had to use it for the Millennium Falcon being caught in the Death Star's tractor beam, because the special edition just wasn't cutting it. The 1997 version caused all kinds of weird phase problems, and the 2004 version is too different to be considered authentic. Since there was nothing else I could do that would sound any good, and because the '93 version is by far the most authentic in this case, I carefully realigned the filtered '93 bass to compensate for the phase shift, and it seems to have worked perfectly. (Hopefully it will come out the same way on other people's sound systems as it does on mine.)
In the course of trying to solve these kinds of issues, I came across a statement by Roger Dressler of Dolby Labs saying that Prologic II in movie mode does not send any low frequencies from its surround channels to the subwoofer when using bass management. This is most likely because it would cause phase cancellation due to the surrounds having a 10 millisecond delay applied to them relative to the front speakers. This upmix also has the 10 millisecond delay, and therefore such cancellation will almost certainly occur in the receiver during playback. This kind of reduced bass is something that I'd actually noticed popping up occasionally in the previous version, though at the time I was at a loss to explain or solve it. This time, hopefully, I'll be able to bypass the problem.
So, I just have to do a couple things along those lines, as well as a few final corrections to the LFE to remove my remaining mistakes. It sounds quite awesome, if I may say. ;) We're almost there . . .