This is kind of a cheezy way of doing it but it does work. Try putting a light around it or in front of it, and then going into the edit properties and drag the lighting to the left to make it a negative number this will pull light out of the scene. I have used this once or twice and had fairly good luck with it, just play around a little with the positioning. I usually change the light color to a gray or something to dull the color a little. Hope that helps.