Let's try to clarify exactly what you would like to do in Poser.  How are you creating the face?  Are you applying morphs to change the model's facial features?  For example, defining a nose shape, enlarging/reducing mouth width, creating a prominent chin, etc.  Or are you enquiring about texturing, which is not quite possible within Poser itself.  It sounds to me that you are probably more interested in the figure's mesh and how the texture applies to it.

Maybe try to explain in detail what you would like to achieve.