Hi,
If you want me to write the project for you I can do so for a fee as it is really beyond the scope of free support here. Just drop me an email. You will still need to define as 4 Mackie MCU devices in Cubase, each with it's own defined MIDI Virtual ports. In MT Pro we look at which virtual port the message is coming from to do the math and tell which encoder to send the message to. I will be able to show you how it is done using my device type however since I don't have a Mackie C4.
Steve Caldwell
Bome Q and A Moderator and
Independent Bome Consultant/Specialist
bome@sniz.biz