Subsoil Excavation

Doing Subsoil Excavation in SS2 was just a matter of getting your Earthwork settings correct and drawing the subsoil lines in the XS. Now that we are in SS4 and not using that dialogue to calculate Earthwork anymore, I was wondering how to go about calculating the Subsoil Excavation. 

I have some ideas for doing it manually by basically just following that old process and then manually placing the Subsoil Cut and Fill numbers in the XS.

You could also try and create a surface for the subsoil so that it plots automatically into the XS. I don;t quite know how to go about doing that and we are having out sub place the subsoil lines in the XS and I don't think we are going to get them to create surfaces for us.

I guess the question is what is everyone doing to get your Subsoil Excavation into your XS now that we are using SS4?