It's great that you want to practice stun shots! IMO, stun shots are the key to any position play. Just set up a straight in shot with the cb about a foot away from the ob. Pay attention to where you hit the cb, at a foot, and medium speed, you want a center ball hit. Shoot it until you can stop the cb dead 10 times in a row.
When you can do that, move the cb back another foot. Do the drill again. This time, you will find that you may have to hit the cb a little lower to get the cb to stop. Do it until you can stop the cb 10 times in a row.
Then, move the cb back another foot, and repeat. After about a week or less of doing this, you will have stun shots mastered, and will be able to stop the cb from any distance.
Now that you can do that, stun shots on an angle become easy. Just shoot it like you would for a stop shot, and look at where the 90 degree line is off the ob. That is the line that the cb will go down.
The farther away from the ob that you are, the lower you have to hit the cb. The long ones become a mixture of speed and hitting the cb low. You want the cb to be skidding when it hits the ob. Try practicing with a striped ball. With the striped ball, you can easily see where the ball is skidding, and where the forward roll picks up on it due to the friction with the cloth.