I havent had a manic episode since the last one landed me in hospital but for me it used to be that changing things a bit helped, just doing something different in the routine.
That being said if your manic episodes are as bad as indicated I would be looking for a way to shorten or prevent it with medication rather than trying to rely on distraction - real mania doesn't give in to distraction, its a driving force of its own.
While I don't experience mania, I do experience irritability and I try to take it out in a constructive manner. Deep breathing exercises can be of some help. Also removing yourself from what is stressing you out at the time by taking a walk for example can also be of some help. Playing violent video games can be a good outlet for anger and violence so long as you don't go out and try to do it in real life like some people out there.
Well I try to keep myself focused on productive activities and also keep a mood tracker here and try to recognize triggers for moodswings and keep note of them. If it becomes an extreme concern I speak to my psychiatrist.