I just ran across the Multimedia over Coax Alliance. It's mentioned on page 90 of the September CEPro; they will be at CEDIA.
Someone please check into what they're doing. Maybe these guys could be, or maybe just want to be, a clearing house for all of these types of products.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw