How to use Blender Internal to UV map AND Alpha map? I've been searching for an answer to my question, but my Google-Fu isn't quite up to scratch to figure out what is likely a pretty simple question. 

Anyways, I'm looking to improve my hair on my character models in Blender Internal. I am looking to use alpha maps to make hair strands appear nicer and rounder while conserving on polygons (as I'm trying to eventually do models for games and animations in a cartoony-stylistic approach, a low poly count is vital to me). 

I was wondering if anyone knew how to have a colour map and an alpha map work together. For example; I want one map where all my strands are on top of eachother on a texture like this:



Where he has all of his locks of hair on the same spot of the texture so that all the strands go with the grain. 

And then I also want a separate map like this:



Where I can control the alpha of each individual hair. 

How can I do this?
I wouldn't do it that way since the pixels counts are so different between the two images BUT if you wanted to, you do have the ability to have more than one UV map - so where you normally reference the default UVMap in the Data panel of the Properties editor, you would use one map for the color image and then add a new one for unwrapping to use the alpha map.