"Can you tell me what kind of education I would need to become certified as an ADD coach?"
So far there have not been certification requirements established for ADD coaching, only coaching in general. The guidelines and requirements for certification for coach practitioner and master coach practitioner can be found at the International Coaching Federation's website.
Coaching an ADDer, however, involves more than what is offered in a general coaches training. I hope to have a full on-line ADD coaches' training program completed by the end of this year, but for now, I train people one-on-one.
Until there are credential procedures established, a certification for ADD coaching specifically will not be available. There are many coaches training programs available, but most I feel are not suitable for ADD coaching. The coaches training programs best geared for ADD coaching are the Coaches Training Institute TheCoaches.com and The Optimal Functioning Institute ADDCoach.com