add a color correction filter to the footage, double click it,in the viewer.. open the color correction tab, bring the blacks down. is good to use a vectorscope I think is called to have a visual idea of what you are doing to the footage. Sorry I don't have y program open to give you more specific detail but you might be able to figure it out from this.
Using the color corrector 3-way, you can do better than just pulling down the blacks.
First pull the blacks down too much, then open the little "Limit Effect" lower section,
click the check next to Luma, and move the two luma sliders on the right
(width and softness) down to the left, keeping the left sliders all the way to the left. This means that only the very darks will be affected by your crushing.