If what you import is vectored, like DWG in particular, you can trace over it, and the cursor will snap to end points etc in the imported tracing guide. That will work with Medeek tools. My normal workflow is to draw plans in another 2D CAD app anyway, bring it into SU and (mostly) trace over them.
If you look at my examples in this post, you can see the imported floor plan I used along with the Medeek model.