Highlighting a brep face from within a C# script

Hello everybody,

I am trying to highlight a certain face of a brep in Rhino from within a Grasshopper C# component.

I have a Rhino brep as input to the component, then an an arbitratry face of this brep is chosen by some C# scripting, and I need to visualize in Rhino which face was chosen. Background is I want the user to be able to interactively sort the faces into several groups/categories and give him some visual feedback on the faces he is handling.

Since this has to happen as a sort of preview within some intermediate settings dialog of the component, I need to directly highlight the face in Rhino. Taking it as a component output parameter in Grasshopper seems not to be an option since the component does a lot more and I can't recompute the whole solution each time a face was grouped.

If there was a way to get the Rhino GUID for a single brep face, when a complete brep was supplied as input parameter into the Grasshopper component, this might be a simple task. But I didn't manage to get the GUIDs for specific brep faces.

Any ideas on how to highlight the face or to get its GUID are warmly wellcome.

Have a nice day,
Michael