Not a "real" solution to your problem, but a useful tip for those that haven't discovered this maybe...

Once you've set up your shader with the texture map(s) for the first zone you can right-click with the mouse and "Select All" then click "Copy.  Once you've done that you can select each mat zone in turn, right-click again, hit "Paste," and the whole shader is applied to that part.  It saves a whole Hell of a lot of time believe me.

The liver is evil - It must be punished.