I think the last lil screenshot in that posted forum link IS what he is talking about. It's a hole, trimmed in a subdiv surface, nurbs-style. Both the subd surface, and the hole boundary are editable.

There are many papers on applying nurbs style trimming to subd surfaces, and I'd kill to see such a modeler built ( Other than one real expensive high-end cad package ).

But for now, I'm pretty darn happy with MOI. :)