The only solution I can think of right now is mencoder, a program bundled with the free
MPlayer. I used it a few years ago to rip DVDs into smaller video files. I know for certain that it is capable of doing what you need, but the downside is that it is a command-line program and figuring it out will take some time and will involve reading the documentation.
On the upside, it should be able to encode the DVD audio into MP3 directly.
EDIT: I have been reading into it, and it turns out it might be a bit more complicated than I had assumed. Just disregard this post.