76-8-311.1 defines a "law enforcement facility" as any building owner, leased, or operated by law enforcement. It also states that "A person in charge of a... law enforcement... facility may establish secure areas". So, yes, a person (no idea who that would be) can post signs and thus make the police station a secure area. And
76-10-523.5 states that even with a CFP, you cannot enter a secure facility.
The little kicker in 76-8-311.1 is that there must be provisions at these secure areas for storing weapons. The question is then if the police station has no place for you to securely store your weapon, then is it in violation of this section. And if it is, then it is not a secure facility at all. If you want to be the guinea pig on this go ahead, but it is a 3rd degree felony if convicted and you'd lose your guns and voting rights forever. So, by my interpretation, if there's a prominent notice on a police station, it's secure and no concealed weapons are allowed.