Me neither. In fact, I was suprised that there was anything that adds your Con to AC. I was fully expecting them to pretty much say that your fort save and Hit Points counted as your defense in relation to Con.
Well, considering that is the only place I can recall seeing Con to AC, and the templates of that book are rarely even talkied about let alone used, I consider it very rare. The template though, is way powerful for the cost and no one should use it as is. The intention of the template is to have a simple way to modify monsters to make them tougher. It is not meant for players and doesn't even list a level adjustment.
I guess you could be a Monk/Sorcerer/Ninja/Duelist with Ascetic Mage feat. Then you could apply your Dex (normal), Wis (Ninja), Int (Duelist) and Cha (Monk/Sorcerer w/ Ascetic Mage feat) to AC.