Here is a P6 way that allows you to get the sillhouette on a prop. I'm using a one-sided square here. Attach a Fastscatter node and make it the same color as your Diffuse_Color. 

Put a back light behind the figure, shining straight at the square. This light must use depth-mapped shadows, otherwise this won't work. The Fastscatter node will translucently light the square with light from the backlight, except where her shadow falls on the square.

You can light the front side as well, or not. Here I placed a table in front of the square and used a dim spotlight to light the front side. You can see both the figure shadow from the backlight and the table shadow from the frontlight.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)