If I understand correctly, you are talking about switching UVs on the fly. I see how that could be more practical than my idea, but I'm particularly interested in converting the actual texture maps.

If you need a potential use case, other than using old textures on new figures: I've been reading through this thread (temporarily switching from Kafka's Collected Works to Antonia's Collected Works for my lunchtime and bedtime reading) and was reminded of bagginsbill's request to make a "height map" for the legs and feet to be used in stocking textures. I created one by creating a throwaway UV map in which the y-position in world coordinates was used as the V and making Poser render on a square using the regular UV map for the positions and let the new UV map drive the color. Not sure if that makes sense, it is certainly a bit convoluted. The point is: the technique could also be used with one-off UV maps that drive special effects, which one wouldn't want to put on the figure at render time.

-- I'm not mad at you, just Westphalian.