sending midi cc

More detail here

Lab: MIDI Output using an Arduino – ITP Physical Computing

One of my unfavoriteist sties, sending CC code is what I do in:-
http://www.thebox.myzen.co.uk/Hardware/MIDI_Footsteps.html

Also look at the technique I have used with the conditional compilation (#ifdef) so you can use the arduino monitor for debugging before actually connecting the arduino through a MIDI output driver to a MIDI input interface into the Mac.