Hi j8jang, there's some discussion on NSided here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5721.2

It works by filling in a patch inside a selection of edges that touch end-to-end forming a closed loop.

In order to use it, you need to have edges selected (not any of the original wireframe generator curves, hide those if they are getting in the way of selecting surface edges), and the edges need to touch each other at their endpoints in a ring like pattern.

- Michael