Basically, this is not possible, because Control Change events are not directly passed to the plug-in. So, the plug-in cannot directly know if a Control Change event happened and which control has been modified. But there is a workaround: You can create 128 “hidden” parameters and override IMidiMapping::getMidiControllerAssignment(). There you can force the host to map each of the 128 MIDI controllers to a parameter. As soon as the host calls IEditController::setParamNormalized() you can override that callback function in order to react to a modification of a MIDI controller.