Hi, I wanted to ask, how should I send my scores to the schools in Australia? Do I need to contact the AAMC to send my MCAT scores directly to each school in Australia, or do I need to send them to ACER, which handles admissions for the the graduate entry programs? Does anyone know the codes I need to give to the AAMC to send MCAT scores to these schools?

Send all the stuff to ACER. That's the point of ACER. Anyway, check the ACER website. Note that if you have taken the test multiple times, I think you need only submit one set of scores.