2-sided materials from grasshopper to rhino to vis

hi,
since i did not find anything usable on the web:

is it possible to define the backface-material of surfaces / faces / meshes / 3d-objects
with a backround material different to front material, like in sketchup?

i would like to paint backfaces of structures in black to have dark sections in my visualisation-section !

thanx for any idea.

stan