I know I had mentioned a while back on this thread, and I have since gotten it to work with another non-SW film, you can use a somewhat complicated multistep phase cancellation with two mixes that are absolutely identical except for the language of the dialogue. It has minimal distortions to the process, but you have to have the sync and volumes match perfect in addition to the mix being essentially the same. It works better on a 5.1 mix since you can separate elements of reverb and such as well, but usually working with just the center channel of the mix or two stereo mixes will work fine.

But, if I remember correctly, there weren't any identical different language mixes for the SW movies, though I could be wrong about that.