Hardware Render Motion Blur or Shadow only Render pass

I'm trying to get motion blur for my hardware render. My objects are driven by bones therefore do not have motion blur applied. I was wondering if there is a trick to get this to work or is there away 

If not I was going to break out the passes and render the objects and then blur them in AE but I need the shadow/amb occ passes with the backgroud, but no objects. Is there a way to render just the shadows/amb occ?

Thanks