[AAR.oner]

--first demux the vob set, leaving you with an .m2v file and an audio file [ac3 or wav]
--sync up the new audio source [wav] with the .m2v in your DVD authoring program, create your menus etc and re-author



numerous programs out there for the tasks...i use ffmpegx to demux & DVD Studio Pro for my authoring [mac]...for windows progs, you might wanna check over at videohelp.com