Under Irix, that used to be very simple; I would simply tell the computer
that there was a
MIDI device on serial port 1 and PD would read that. No such luck with
Win32.
Ah, the beauty of *nix...
No experience but I'd try to abuse drivers from Roland, Yamaha, Korg,... Some of their gear (keyboards, digital mixers, sound modules) has a "to host" serial interface for "midi without midi port".
Johannes Taelman