I'll see if I can't work something up. It'll be good to have an excuse to learn KiCad.
I'm sure there are plenty of out-of-warranty folks that would be interested in tinkering, and installation should be no harder than something like a Kenton MIDI to CV converter kit. The toughest bit is probably drilling the case.
IF I ever get anything done it will not be a kit, but probably a PCB available through OSH Park or something like that.
I'll post here with any updates, but it's not a priority project for me so don't bug me for updates