Without Windows Style Builder, you can not change the font colors. It simply isn't possible. I was looking for it once too, for hours even, and i didnt find anything. You will have to purchase WSB from
Ave's Vista Style Builder, to be able to do.
You won't regret buying WSB, it is really really much better than doing it via a resource tool. It'll save you time as well, and make you able to change more images and properties than you are able to in a resource tool.