Have the player perform each step and hold.
1. Have player stand still with glove side foot forward, ball in glove. (like they just made the catch)
2. Have them move their back leg forward (no hop yet), moving the foot high and in front of the other leg, planting it perpendicular to the target.
3. The other foot is now behind. Have them pick up that foot and bring the knee up about belt high with the shoulder pointed towards the target.
4. Now have them step and throw As they become comfortable with the movement reduce the hold period until it is one natural movement.
There are many times when you can't get yourself set up to use a crow hop. So how do you gain momentum to make a long throw? The answer is a shuffle of the feet. It's very similar to the type of shuffle you would use when leading off a base. The difference is that on the last shuffle before throwing the ball you will cross your back leg behind your front leg, plant it, push off and throw.
Below is a shuffle being performed from right to left. The fielder has just backhanded a ground ball and has planted his right leg. He's too deep in the outfield to be able to just step and throw. So to gain momentum towards his target, he is going to shuffle towards the target and then throw.
The example above was on a ball that was backhanded, but the shuffle can be used on any play. Some players prefer this method to the crow hop and use it even when they could have used a crow hop. Personally, I find I can get more on the ball using the crow hop, but the shuffle throw is still a necessary skill that you will use on a regular basis.