Hi IronManRipken,
Glad to hear you want to learn the knuckleball. A number of good MLB pitchers were able to resurrect their career with it. Most recently, Tim Wakefield.
Here, is one way to throw it:
1. Bend your middle finger and index finger of your throwing arm and grab the ball. (You know when you are doing it right because your two knuckles should be resting on the baseball).
2. Your ring finger and thumb provide support to the pitch and should be placed on the sides. (In other words, the knuckles are on top of the baseball and ring finger is on the right side of the ball and the thumb is on the left side of the ball.
3. After you grip the ball, you will throw the ball with a fastball motion. The only difference is you are not focused on trying to throw this pitch very hard. Instead, you are looking for a lot of movement and so you will want to throw it with average arm strength and let the ball naturally.
4. As you practice this pitch, you may find that you have more movement and control by having your knuckles grip one of the seams or even extending one finger forward and using only one knuckle. It will take some experimentation on your part to find out what works best for you.
You can also, check out the book, "The Knucklebook" by Dave Clark to get other tips.
Best,
Jack Elliott
Baseball Training Tips