Smithie ST3 sends MIDI commands to all MIDI ports available. So if another app declares a MIDI receiver port, ST3 should automatically send to it. The MIDI send port of ST3 is only active as long as ST3 is running. So maybe you could try to first start ST3 and then your midi player.
PaulMichael Please don't hijack threads with other topics.
What you see is most probably a bug in the migration code I have fixed in version 3.0.3. That version is currently in review by Apple and will be available shortly.