How to add basemap to MapDocument using arcpy?

Hello - I am using ArcGIS 10.1 with Python 2.6. I am using arcpy to work with an MXD template that I read using arcpy.mapping.MapDocument. I want to add a basemap to the default dataframe (I have a URL to the basemap), but after searching high and low, I can't find a way to use the URL to add the basemap. I see alot of examples of adding a layer (.lyr file) but nothing on how to add a basemap. Any info on where I can find out how to do this would be greatly appreciated.

Thanks - Peter