Python to Change Selectable Layers

I'm just wondering if it's possible in python to change the selectable layers in a map document. I've built a python add-in that allows a user to select a group layer and when they select that group layer only the layers in that group layer will be selectable.

I can't seem to find a way to do it. I mean you can do it manually by setting all the layers want to be selectable in ArcMap, but is there anyway to do this through python?