Most high end modellers that create characters for poser do it in modelling programs outside Poser, then import into Poser. About getting the right facial features, takes knowing how to model, and how to model and stylize human face.
I was at a local bookstore recently and saw that there are quite a few books available on how to draw anime characters. That's a good start. Once you can draw one, you can start learning how to model one in 3D.

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