I want to be able to composite my own shadows onto my poser figures in live action animation. I want to be able to create awesome shadows at many angles, anyone know of the best methods to do it?

Live Action Animation? Do you mean that your Poser Guy is not a still but animating or do you mean that he's going to be comped over captured film or video? And what did you mean by "onto your poser figures"? I ask because it will make a difference to my answer. But here's my guess. If you have the comping software like After Effects you can take the matte channel of your character and lay it down, skew it and fill it with black,soften it. But there are a lot of hassles that come with that. But it would be one way of doing what I think you want to do. I hope that helps in some way.

yes it is being put into live action captured video