Trouble ripping a dvd with a strange framerate

I've got a dvd that I'm trying to rip that has a very strange framerate
issue. The source framerate is 29.97, but it's not telecined; there are
no individual frames that show any interlacing at all. Rather, it seems
to have complete duplicate frames inserted into it to bring it up to
29.97 from the original 24fps of the film source.

How can I configure transcode to properly handle this? I've tried using
ivtc, but it left me with gaps; like it was removing too many frames.
I've tried ripping it without any filters, but it left visible pauses
where the duplicated frames are. Any help?

FWIW, the dvd in question is Pan's Labyrinth, and a google search turned
up a comment about a similar problem in someone's rip on a torrent site,
so apparently I'm not the only one struggling with this:
http://www.google.com/search?q=pans%20labyrinth%20frame%20dupe

- Marc