Recoloring Alpha hair. How to make a "standard" colored base?

I usually put two textures on different layers (one from which I will take the color and the second one which I want to recolor). I make sure I can see these two textures at the same moment and I select colorize tool from colors menu. Then I pick the color from the lower layer and I'm trying to adjust the color to match. When I finish I save it as a present. Sometimes I also use Hue-Chroma tool. That's what I am doing but I'm not sure if it will work in your case. However, I hope it can help you a bit.