[PyMOL] Creating Contact Surfaces in Pymol

Is there an easy way to refer to/select a portion of a molecular 
surface that is within a given distance of another molecule's surface?  
I'm trying to generate some graphics for a presentation on a signaling 
pathway, and I want to show just the part of each peptide's solvent 
accessible surface that is making contact with the binding site.  
Ideally, I would like to be able to color this, at least in a 
contrasting color to the structures of the components, but preferably 
tied to electrostatic potential or hydrophobicity.  Has anyone ever 
done this, and if so, can you spare any advice?

Thanks,
      Andy