i really don't know Alabama geography at all, but you can try:
Montgomery Brewing Co Root Beer 12 W Jefferson St, Montgomery, AL
http://www.montgomerybrewpub.com/
Zea Root Beer Zea Restaurant locations
http://www.zearestaurants.com/
besides that, i will agree with Kevin, grocery stores, gas stations, convenience stores, brew pubs, beverage distributors, etc. you just have to drive around and call a lot.
_________________
anthony's root beer barrel
http://rootbeerbarrel.com