Custom unwrap surface

Hi All,
we are developing a custom unwrapper for Rhino for more accurate unwrapping, it works well enough for meshes and I would like to use it for surfaces. Is there a way to write the texture coordinate to the surface?

I assume that the current workflow for Rhino unwrapping is that the render mesh is unwrapped and once the surface is modified, the old mapping is remapped to the new tessellation of the surface. I would like to tap into this workflow with our custom unwrapper.

Any idea on how to accomplish it?

Thanks
Alberto