You mean specular or pearlescant paint, I'm no master at this but the way to do it is at alter the colours of the Spec sheet of the textures,  most people use shades of grey but if you add lighter or darker shaded colours it changes the colour underneath dependant on the light.

The Man to talk to Is Chris Brisland over at Eagleskinner http://eagleskinner.com/EShomepage.htm.

some of his stuff








Bruce