Okay, I've got this figured out now. I was able to extract a DTS mix and save it to a single multichannel .wav. I had a problem with the bass channel being corrupted but fixed that with an upgrade to the latest DVD Audio Extractor (just released in July).
So, I have finally experienced Bohemian Rhapsody in 5.1 sound and it's pretty cool. Believe it or not, NeroVision somehow knows to take the 6 channel wav and put the stuff into the right place in 5.1. That was the test run... now it's time to try it with a complete disc. I shall post my results later.. probably in the Queen section since I'm working with those mixes first.