I don't think you can, at least from Mac OS X. However, there are two workarounds:
Option 1
Using Disk Utility, make a disk image of the DVD (dmg file).
Advantages: No external programs needed, dmg format supports transparent compression
Disadvantages: dmg format is not cross-platform
Option 2
Using MacTheRipper, rip the DVD to AUDIO_TS and VIDEO_TS folders.
Advantages: Cross-platform format
Disadvantages: No compression, requires external program