Hi Ladd -- Yes this can be done.
You'll see my reply to your question on the DVDRHELP Mac forum, and I'll post the same info here.
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HOW TO COMBINE MORE THAN ONE MOVIE ON A DVD (MAC OSX)
1) Rip each title using DVD2ONEX as "Movie Only," using a custom size. If you want to put three episodes of something on one disk, and they are roughly the same size, divide the target disk size (4472) by 3 = 1490. Set your custom size to 1490 MB.
If you're combining a double-sided flipper disk, or two movies of unequal size, figure out the proportions and set the custom files size accordingly.
Rip into separate folders. Choose soundtracks that are .ac3 (not DTS), as I'm not sure the other OSX tools you'll use can handle DTS.
2) Use Extractor 0.95 (http://denisx.dyndns.org/extractor/) to extract the elementary streams (.m2v and .ac3) from each of the VOB file sets you created in DVD2ONEX.
In some instances, you can queue up all the VOBs in Extractor and rip them as one single m2v/ac3 pair. Some titles are authored to have a short kicker script as the last chapter. If you view a title from you source disk in OSeX you can check the length of the chapters -- if the last one is 15 frames or so (very short) it's a script. This can sometimes prevent DVDSP from handling the file correctly, and will mess up your file if you rip to one big file using Extractor. Experiment.
So, with the m2v and ac3 ripped from each of your episodes/flipper sides, you can now assemble a disk using DVDSP or Sizzle.