I have not read this article, But I have in the past used a pliugin from Cebas
http://www.cebas.com/products/feature.php?UD=10-7888-33-788&PID=38&FID=328
You can render out from max and it will creat a multiple layered .psd file with alphas,,,,that easily allows you to change the color easily.
Check out the link, I think it will help