Typically, for print and web designers, we use a spectrometer (or another type of color reader) that tests the levels of a print or photo to understand the mix that makes certain colors.
If that's something you need, you'll be testing a lot of colors on a photo, but it works.
Otherwise, I recommend checking out the some of the 3D design forums (we are required to build hair structure, texture it, finilize it -- takes forever) because they can give you some color samples for hair.
The forum for Lightwave 6 is http://www.postforum.com/forums/list.php?f=22
(this is the program they use to build movies -- especially Lucas Arts and Pixar)
You may also search for forums for Strata 3D studio pro and Lightwave -- or their direct websites. It's your best bet.
I typically use 3D to design cars and various non-living objects for video, web and other medias, so i can't help you that much, but I can lead you.
I'll check the programs real quick as well and see if they have a fixture.
You can always get a photograph of someone with hair and check the levels in photoshop? If your using ProCreate Painter, it'll read the mixes -- I don't know about Corel photopaint or paint shop, I don't use them.