The problem with using the ambient setting on the PoserSurface node is the potential of washing out textures if the ambient value is too high.  To work around this, you can surround the figure/object with a primitive, crank up the emission, and under the Properties tab, make the surrounding primitive not visible in the camera.  You can even change the primitive's emission color for a cool-looking color.  This will only work for Superfly renders.