You can't. At least not yet. As far as I know, AA12 is still reserved for military/government use only. I don't think it even made it past the testing and approval stages yet. I know that a couple of companies got their hands on a few guns for testing with robots (remote controlled chopper, automated and remote-controlled turrets, etc.), but I have not seen anything about a release to the general public.
In any case, I doubt that a full-auto version will be released for civilian market any time soon, if at all.