What you need to keep in mind with leg length discrepancies is that it can be a "functional" or "structural" difference. For example, If your muscles length/tension relationships are off, you may hold one of your legs higher than the other due to the hip being lifted higher from muscle tension. If it's structural, then no matter what, your leg length is one inch different, but with lifts and a commitment to integrated functional exercise, he could minimize alot of the problems that occur due to the stresses his own body puts on itself.
In a quick and quite hopeless plug- Greg, if you are listening, check out www.tridfitness.com and I'll be happy to have a consultation with you to discuss how I could help you.
-Eric Sp.