[PyMOL] grid/cube representation

[Sebastien Gerega]

As a follow up to my last email asking whether there is a way to make 3D 
grid representations of molecules....
I have found a picture of the kind of thing I am after. Is there a way 
to make anything similar to this 
http://www.techfak.uni-bielefeld.de/ags/ai/projects/docking/images/align.2ptci-6pti_small.png 

with PyMol?
thanks,
Sebastien