I've had a fair bit of success scrubbing music and sound effects from dialogue using Sony Spectralayers. It isn't 100% perfect, and it can be quite laborious, but I have been (very) slowly picking away at A New Hope for a few months and I'd say I now have about a third of the film's dialogue in a usable state. I haven't tackled Empire at all though, so I can't offer any clean dialogue from that one.

Spectralayers is quite good for removing more 'spare' bits of the score (a single flute or horn, for example) -- there are occasions where I've been pretty amazed at how easy it can be to seemingly obliterate the music -- but it gets a lot trickier when the full orchestra is swelling behind a line of dialogue. Still, with trial and error and a lot of time, it can produce some really good results. Food for thought, I suppose.