pitcher in the first game of the series. Instruct him to throw nothing but (slightly) inside heaters from the chest up to the neck. If you go 3-0 to a batter, the next pitch better find flesh. If the pitcher gets tossed, send in the next one, and repeat until they back off the plate. Set the tone early. Lose the first game if you have to, but don't let the other team get away with that, ahem, strategy.
If you get hit enough, you'll back off the plate or you'll spend time on the injured list.
If the umps don't like it, respond quietly and gently... "Mr. Umpire, the batters are hanging over the plate. It's very difficult not to hit them when they are in that position."