Attached Link: http://www.3drender.com/light/3point.html

3 Point Lighting does not mean you only use three lights--it means there are three types of lights (Key, Fill, Back). You can have as many lights as needed. You're only going to be able to do so much with Poser's limited light types and poor render engine, so your best bet is to do most of the stuff in your paint program such as softening shadows, lightening areas, darkening areas, blurring, dof (depth of field), reflections, refractions, and so forth. Go to the link I provided. It has a tutorial which you can follow. Although it's not Poser specific, the general method can be applied.