In the picture you can just make out the Pro Micro "Soarer's Converter," which I flashed to use a firmware that includes the VIAL graphical configurator. I then taped that old Micro-USB cable to secure it and stuffed the whole thing into the case.

Hardware wise, this is a simple PS/2 to USB conversion, but because it was made for a bit of commercial lab equipment, the software side got a little weird, almost like it was high on something, LOL. The numpad doesn't include the usual math operators, NumLock is non-existent (and in fact this keyboard forcibly turns it back on if you find a way to turn it off), there's no Windows/Super key (not uncommon on older designs), 34 of the keys above the main clusters actually send combined keys (F9+A through F9+Z, then F10+A through F10+H). Someone else had already figured out that using F9 and F10 as your "layer switch" or "Function" keys is the way to unlock that, so I did the same. I only had one extra layer (plus two "Combo" keys) to play with, so I was only able to convert 28 of the 34, but those 28 now do pretty normal stuff: F keys, navigation keys, media keys, etc.

The other quirk is that, while the slightly longer spacebars (7 key "units", versus the usual 6.25) are not rare for keyboard nerds, the stabilizer rod for this one is on slightly nonstandard spacing, so I'm stuck with it until I can source another one. Luckily, the caps themselves are pretty decent.