Hello, Ray. I think this is not possible by default way. But there are trick, that can help you. Each of richfaces components have predefined styles, rich:tabpanel is not exclusion. You can giv each tab specific id and redefine rich:tabpanel css-classes for particular tab, according to skin, but there are lot a work and you must generate all images by hand.
Andrey, thanks for your response. I will play around with it.