From the configurator FAQ:
I have a Keyboard that I want to add support for
Awesome! Open up a Pull Request for it. We’ll review the code, and merge it!
That means the only way to use those files would be to clone Massdrop's git repository and then submit the pull request, or ask someone at Massdrop to make the pull request for you. As some boards are already available the second option might not be as unlikely as you think.
Good luck