I hate to tell you this, but it is a long and complicated process. At least it was for me. I got Coppermine changed to almost the colors I wanted for fiblack.

You can see it here:

http://www.bootleghollow.com

The changes have to be made in the modules/coppermine/themes/style.css and in the modules/coppermine/themes/template.html

I just played around with each setting until it came out right. The easiest way I found was to open up a program like Dreamweaver, and look at the individual settings on the css. I tried to match them to the colors found in themes/fiblack/styles/styles.css

Hope this helps a little.