I don't think there's any real secret to the lefty-righty thing. If anything, you have an advantage: you can stand facing each other and he can try to mirror you as you throw. Us lefties have to learn to flip the right-oriented world around all the time anyway. :roll:
Use terms like "glove arm" and "throwing arm" instead of "left" and "right".
His hands are probably too small to get the ball out of the palm, but he should still be able to get the right two-fingered grip. IMO.