Rendering shadows on a transparent background

[afin83]

I'm still fairly new to blender, sorry if this is a n00b question - I'm trying to find a way (or even if it's possible) with cycles to render and object on a transparent background AND include the shadows that object is casting and any bounce light it may be receiving.

I've tried a few different approaches:
1. Getting the transparent background is straight forward - output to RGBA and check transparent in Film, this works perfectly if there is no background. However I lose any bounce light and shadows.
2. Render layers, this is better if I have the object I want on its own layer and render that, from what I can tell (I may be wrong) it looks like it's receiving the bounce light, however its shadow that's being cast onto a floor plane on a separate layer is not included.

Is there a way to get shadows on a transparent background?