After some initial playing with my Arduino Pro Micro controller, I wasn't sure if I'd be able to make it work without some really intricate programming on my part. At first, I couldn't find information on what exactly I needed, which was 'how to use the Pro Micro as a keyboard matrix decoder'. I wasn't looking forward to doing it the hard way. Even less, as the information I did find indicated that I wouldn't just be writing code in the friendly Arduino IDE, I would have to get guts deep into some cross-platform C in order to create a completely new firmware.
Happily, I found an online keyboard firmware builder that would let me copy the raw data from the keyboard layout editor. From there, I could edit the keys and create a .hex file tailored precisely to the controller.
I have my diodes on order. My Cherry MX reds have arrived, as well as my keycaps. I haven't figured out the case as yet, but hopefully once I have the diodes I can warm my soldering iron up to temporarily connect everything up so that I can validate this whole thing will actually work.