From a pitching tip email-
Coach Steven Ellis here with another baseball pitching tip...
Long toss is a great way for pitchers to work on their changeups.
At various distances, I threw 1 changeup for every 3 fastballs.
By long tossing with a changeup grip, you are training to have fastball arm speed, which is essential for fooling batters.
I started off gripping the ball with a circle change until I could control it. Then I played with the finger placement and pressure points to refine the pitch.