Hey,
I started studying music when I was 10...the FIRST thing the teacher had us do was 'tap and clap' with our feet and hands.
On the first beat we tapped our feet, on the second beat we clapped our hands...at first we did this with the director guiding us, then with a metronome, then with a piece of music. We must have looked pretty silly, but it really got the clock in our heads in sync with our bodies.
Afterwards we brought out the instruments and learned how to play simple notes in time with the metronome...in your case it would probabably be best to count numbers. He'll have to understand the concept of beats v measures (4 beats to a measure, 16 measures in a verse, etc.), so have him do '1-2-3-4 2-2-3-4 3-2-3-4 4-2-3-4' kinds of patterns.
These are all simple quarter note patterns, if you're feeling brave you can move on to 8ths, dotted notes, etc.
However, if he has potential like you think he does, he probably won't need to do this stuff too much as his internal clock is already working well.
As for the music side of things, this is a little different. I feel that this is a little harder to teach, especially if you don't know how it works yourself (I don't know if you do or not, though). It helps to have an understanding of keys, chords, and scales so you know what notes 'work' at any instance during the song. Some people have a natural gift for knowing what pitch to sing in for melodies and harmonies; I am not one of these, so I usually have to play around on a keyboard finding the notes which sound good. I record the notes into a sequencer and play them back to the singer, they then match the pitches with the words and it gets recorded. Having a chord book handy is very helpful, you can cheat your way through this by looking the notes up and choosing the ones that fit, then creating a melody from them.
Take care,
Nick
