So if you mean you are doing an initial course on the S76 in the US, and once completed you wish to get "COMMAND S76" put on your CASA licence, you will need to send the paperwork regarding the training you completed to CASA in Canberra. I imagine they will expect to see that you completed a structured course including type technical training and 10 hours flight training, same as if you had done the course in Australia.
You will not get an S76 type rating on your FAA pilot certificate as there is no such thing.