An "MSD"?
Since Orbiter is intended to simulate real life physics and gravitational mechanics, tell me how it would be possible to
achieve what you want? Not even a car can stop instantaneously.
The closest you can come to what you want to do, is to ensure that you are using very powerful engines, flip your craft to
point along your reverse route and blast like hell.
Still won't be instantaneous. But then, that is not what Orbiter is about.