Question

I was more specifically trying to determine whether a MIDI controller like the AKAI MIDImix could be mapped through the host computer on which Universal Controller was running but I guess in the absence of any keyboard shortcut type assignations the one would not talk to the other in any useful way.

Answer 1

MIDI mapping (as referenced in the prior related answer) is not possible directly to the mixer.  MIDI Learn is capable of controlling functions within Studio One 3 only.

Answer 2

This can't be done with official software, but can be done if you create a MIDI-UCNET bridge and send UCNET commands yourself. There's a couple of projects on GitHub reimplementing the UCNET protocol, such as https://github.com/featherbear/presonus-studiolive-api