Good point about the kid's willingness to learn. If he is willing to learn, then my suggestion is to have him try a few different things: 4-seam, 2-seam with the laces, 2-seam across the laces.
In my opinion ... 4 things that will help him with getting optimum velocity, movement and control are:
-- Try to stick with 2-finger grip. The closer together his fingers stay (without losing control) the more force he'll transfer to the ball, and the better the movement.
-- Have him make sure his thumb and middle finger cut the ball in half. A small difference on the ball can lead to a big difference in hitting locations at the plate.
-- Check his hand in the glove before he starts to throw. Make sure his hand is directly behind the baseball. This set-up can help keep the hand behind the ball throughout delivery; helping with velocity and control.
-- Have him "aim small". Rather than aiming to hit the "glove" have him focus in on a spot in the glove about the size of a dime, and ask him to throw the ball through the spot (not to the spot).
Of course, if he will develop his funtional strength, and develop efficient, repeatable mechanics, this will go a logn way to help as well.
Good luck to you and your players.