The local module builds we have documented at the moment [1] should work if you have an access to the Fedora infrastructure (==internet connection) and your packages are in the Fedora dist-git.
I know that Merlin (merlinm) is working on tooling that allow you to do local module builds without relying on any external infrastructure, basically the way mock works with standalone packages today. He's submitted a talk to Flock [2] about it. I know that not everyone can attend, but he's probably a good person to talk to, and if his proposal gets accepted, there will be a recording. And the docs should get updated, too, when it's ready! So.. it's coming