Adding AC+ after the fact is the same as with an iPhone. You either take the AW to an Apple Store or chat/call the AppleCare people. If the latter, they email you a link to run a test program on your device to verify working order, etc. I'd do it over the phone; did it that way once when I didn't add AC+ on a new iPhone at preorder and it took about ten minutes for the whole conversation.
	
		
			
		
		
	
				
			 
 
		 
 
		