It's the same for Zbrush, you have to import the original figure and morph that. Then you can use Posers Little Helper to make an injection file (or you can just take it into another program and export the body part you morphed, which I'm asumming that's what you did).

And to nruddock, I'm pretty sure that it is not Quidam that caused that, just like it's not Zbrush that caused the problems, it's Poser.

When you export an obj from Poser you have to select:

Weld body part seams

Include body part names in polygon groups (DO NOT select "Use Exact Internal Names Except Spaces")

Include Existing Groups in Polygon Groups

I normally do not use the export option for V4A4G4S4M4H4K4 though, it's too complicated, I'll usually use the original object or take it into Hexagon (or any other modelling app that will export individual groups and retain the groups and UV's) and export the head (or whatever body part I need) from there.

:) Good luck and congrats on getting it to work on atleast a few of your custom characters.