I’m sure there’s a way to do this digitally, but…
One way to do it --in real time-- using hardware is to get a modern Surround Receiver or preamp with analogue outputs for each channel (The NAD T748II has these, for example). Make sure the receiver is playing back the DTS-Master Audio, play the blu ray and record the output of the center channel to whatever recording system you have. Though I haven’t done this specifically with Star Wars, I’ll still bet you’ll end up with a very high-quality recording with almost 100% dialogue, with a few center-panned sound effects popping in as well. Most modern movies have the music panned to some combination of the L, R, and surround channels.