The "fast track" is countless hours practicing on the court. working out in the gym, and playing as much competitive tennis as you can. A good coach is almost essential as well. Note, a bad coach will not help you much, and may hurt you in the long run. In my opinion you should not teach/force him to play a certain way that is effective against lower level players, only to plateau at 4.5. Let him work hard, develop his own identity, and then see if he can maximize his potential. Why stop at 4.5 when he can go to 5?
Wish him the best of luck.