This will be a bit vague, as I'm at work and don't have C6 here, but hopefully it'll point you in a useful direction:

When you're importing a Poser figure into Carrara from the browser, an option pops up with something or other about using target helper objects.  I don't recall exactly what it's called, but do import the target helper objects.  Then, you'll have the green boxes that Dwarg mentions; they're at the end of IK chains on the characters.  You can manipulate those to handle foot movements via inverse kinematics.  If you don't move the helper object associated with a foot, the foot won't move.

That's not entirely true, though.  The foot will not tesselate, but it will rotate.  So, I've had to go back and clean up the rotation of the feet, but their positions stay pretty well locked down. 

Hope that's helpful.

 - Dex