It is on this page in the Rhino wiki:

http://en.wiki.mcneel.com/default.aspx/McNeel/UVcWrap.html

This works on meshes and nurbs, but when you input a nurbs object, it will just extract the render mesh into a new object, then hide the nurbs object, then unwrap the mesh. By default, Rhino polysurfaces have packed UV coordinates already... Clement's instructions are pretty clear about how to use it properly. As he mentioned, it was built using scripts so it has limitations. And McNeel is already starting to work on a true Nurbs unwrapper and UV editor. But Nurbs unwrapping probably won't have any benefit except to those people rendering Nurbs objects directly in Rhino...

jonah