How do I backup my Xfinity internet gateway's configuration to a file for manual restore as part of my DR procedure?

Im looking for a way to backup my Xfinity gateway's configuration data to a file (txt or xml)

presumably from a command line interface using a hyper-terminal like application.

Then also, what would I need to do to then restore the backup from file onto the same gateway after a factory reset? Also presumably from a command line style interface / terminal app.