When I run the WS-MAN samples in the 3.0 SDK, am I making the AMT run in DASH mode? If not, what do I need to do to make the AMT run in DASH mode?
That is a very good question. As you know, Intel AMT provides two modes to interact with it - one is legacy interface using SOAP/XML and the new one in WS-Man. DASH is a standard that defines the specification on how manageability on desktop and mobile platforms in performed. You can find some good interaction regarding DASH here.
Coming back to your question, AMT does not have any DASH modes. Intel AMTsupports the DASH standards (which utilize WS-Man for communication) and much more beyond the DASH profiles. After provisioning, you do not have to do anything to AMT to make it respond to DASH requests.
Hope this helps.