yo want a product/system to run on a mac that outputs broadcast in a "frame-like" fashion.
if you are using this for broadcast, like the real cable news etc, I suggest looker further than you can here on MR and do technical research. because I think those are either "all in one machines" or large products including software and hardware possibly.
if you are talking about making some video and text you have to look like a news channel, and if there is some sort of template for it, I have no idea. But from scratch its rather simple. That would allow you make something you can plug stuff into, but you cant just type in and hit return and expect it to BAM show up on your CCTV setup.
be a little more detailed in what you are looking for