There is two ways to do it yourself in Poser (that I know of). Method 1 is to colour in your texture and see where the colours are. For example, say I fill in the template with a spectrum of colours starting with red on the right through to blue on the left. Render the template and see where the colors go. From the render you should be able to figure out what area is where, although you may need to do another test with the spectrum going from top to bottom. Method 2 is to use the grouping tool. Mark the rectangular area (facet) you want in red, check you haven't selected anything else. Create your group and assign a material to the group. You can now select that material and apply a texture to it which doesn't have to cover the other areas.