Teach him to shoot instinctive with both eyes open. If that seems impossible (it's really not, you throw balls instinctively you can shoot arrows that way too) he could try looking into a sight similar to this one: http://www.kineticbows.com/index.php?category=26&PHPSESSID=765a7f2d1de3d1 cd2a738acc7ec8bc5a
It combines instinctive with sighting. Kind of a instinctive aid. Your eye naturally finds center. I'd suggest doing the patch one more year and then going instinctive. I shot my compound that way for years. Most shots are 20 yards and under and he should be able to get that proficient easily. I'd also suggest roaming the woods and shooting stumps, twigs, and leaves over target shooting. It will help him instinctively judge distance and shoot in hunting situations.