After running into a few issues in programming the midi filter rules, I think the following example should be added to the wiki: https://wiki.zynthian.org/index.php/Configure_MIDI_Filter/Router
Map any channel CC59 to Channel 15 CC120:
MAP CH#0:15 CC#59 => CH#15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15 CC#120