What version of Poser?

In your render options, you can render your shadows separately.  Do one render without shadows, and another with just shadows.  Copy/paste one on top of the other in your graphic program.

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi