Logic Pro 9 IAC from Terminal to Environment?


Hi all, I am wondering if the IAC Bus can get the MIDI from an app that ,for the moment, only runs in the Terminal[later it will be a stand alone app] to send 4 MIDI files via IAC to four VSTi Arrange tracks via Logic's Environment to a channel splitter to get 4 MIDI channels. Or do I need a transformer to change the IAC's output to MIDI channels? Can the IAC input be MIDI files?
Thanks for any help-I can't find much info on the IAC, In my old Logic Pro 8 David Lahmani apple certification manual he mentions the IAC but says nothing about it, so I haven't ordered a Logic 9 from him. Owen-do you explain IAC use in your new Logic pro 9 book?