As reported in this message on the OM users group front page, port number does not work in midicontrol objects.
This will be fixed in the next update (6.9.1 or >).
As far as I can tell however MIDI port works with midi-mix-console
In OM, If I enter a non-0 port number (for example, # 1 and # 2) into port-input of [midi-mix-console] or [midicontrol], the data will be sent to port 0.