bluetooth board communication to hardwired device?

Well vehicle is irrelevant, it is an aftermarket alarm. I plan on using a Compustar CM5000 series brain. The vehicle in question currently has a CM3000 series system installed which is not serial capable, whereas the CM4000+ series are. It has an RS232 port, but I am unsure of the protocol used. I am in the process of obtaining one to experiment with.