I recently received my KBDFans KBD66 from Massdrop, and I love it! But it runs TMK, and my Planck runs QMK. I thought it would be nice to run the same firmware on both, and I wanted to try out some neat QMK features like space cadet shift keys.
So, anyway, I have a fork of QMK with the kbd66 firmware added. It has support for Qwerty (Fn-Q) and Dvorak (Fn-W), and can switch Alt & Gui keys for OSX support (Fn-A) and (Fn-S).
Current limitation is that it's currently just ISO layout. It should be relatively easy to add ANSI if you've used a different layout for your kbd664. I didn't want to add ANSI right now because I have no way to test it.
I plan to submit this to the original QMK repo. I just need to tidy it up a little bit, document it, and open a PR. If anyone would like to try it out in the meantime though, any feedback would be gratefully received!
You can clone the code from here:
https://github.com/judy2k/qmk_firmware/tree/kbd66 (note the kbd66 keymap is on the kbd66 branch).