Set players up at all three bases. They are independent of each other because each base has different rules for a ball in the dirt. A coach pitches from the mound and mixes in good and bad pitches to the catcher.

Any time a ball is about to bounce the whole team yells "Dirt". This helps you make sure everyone is paying attention. Base runners on first should automatically go when the ball is in the dirt. Runners on second should react to the ball in the dirt by getting a good lead and deciding if they can make it safely to third. If the ball gets away from the catcher they should go, if the catcher digs the ball out of the dirt, they should return to second. Runners at third should follow the same principles as the runner at second, get a good lead, and then react to whether the catcher digs the ball out of the dirt or not.