Midi shift-key function

Hey there, I've only just got M4L and for my first task I am trying to replicate the 'shift' functionality from an OP-1 keyboard when using it as a midi keyboard. So if I am holding a one button down another button will send a different CC message than it would otherwise.

I've run into a few things, I am using 'ctlin' to capture the cc messages
-Is there any way to monitor how long a cc message is held down or does it always send two bangs, from key up key down I guess. Or if not is there any way to separate the midi cc key up and key down messages as you would with a computer keyboard
-Is there a way to make an integer toggle between two values at provided message or bang?

I hope this all makes sense, I'm feeling a little overwhelmed, I managed to make a rudimentary device that output cc's on different midi channels, not realising I couldn't change the midi channel an ableton live track was outputting so that was a bit of a failure but good experience.