I'm afraid I didn't do much research on vitiligo, at the time I was hell bent on finding a cure for melasma. My understanding of vitiligo is that the melanocytes themselves are underactive, or totally non functional, the opposite to melasma, where they are overactive but still require copper in order to convert tyrosinase into melanin. My first thought was that you could treat with copper (topically though, too risky to increase dietary intake, too many other adverse effects), and I guess you could try thta, using a cream with added copper, but my guess is that it wouldnt work because the melanocytes wouldnt do their job. I found the links below, the middle one has some possible alternative treatments but I don't know how effective they are.
Sorry I couldnt be of more help!