C4D Object buffer to After Effects

Hi,

I've rendered out a scene from Cinema4D with multi pass as PSD sequence. I've imported the image sequence, ambient occlusion and shadow passes in fine.

I now need to get the alpha channel created from the object buffer in but can't seem to figure out how?

When I open one of the PSD sequence files in photoshop I can see the 'Object buffer1' in the channels palette so it's there but I just don't know how to get it showing in after effects.

Cheers,
Steve