There is actually a much easier way to perform some of those steps. First off, in MacTheRipper you can choose to demux the audio and video at the same time the ripping is being performed, and select which items you actually want to end up on your hard drive. Six individual AIFF files can then be obtained by decoding the AC3 with a program called A52decX.

I haven't yet found how to get a precise list of a dvd's chapter timings, though, so I've always had to create new ones myself. Still looking for a way to do that.