I'm sure your looking at a very custom post to do that. I really dont have the first clue where to start. Did you talk to your reseller about it?
Does this head change with the tool change arm, or do you put it in manually?
So then you'll drill in the YZ Plane with X- or X + as the spindle (drilling) axis). Iv'e done it with Mastercam . Dont know how to handel it in EdgeCam.