Assuming you don’t have a controller which can be configured to step in 12’s ,
then you’d be looking at a loopback† with a couple of Rescales:
-
the first squashing the number of CC values down to just 11 and
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the second Rescaling to 4, 16, 28, …, 64(=+0 semitones), …,124.
If you have a controller like a Keystep which allows a clamped (but not stepped) range, you’d only need the second Rescale.
† the loopback would be of the simpler kind where the Rescaled values leave a port and then are picked up as mapping when they re-enter MH (no safety filters needed)
Use the Loopback Mapping Tool – it solves the issue of MH getting confused between the original and scaled CC when setting the Semitones Map.
1.15 EDIT
This is now much easier with virtual mappings. See this entry in Virtual Mappings Techniques Tutorial