As I understand it, the Large Format Displays are nothing more than extra large computer monitors. There is no way to get it to act as a tv all by itself. Looking at Newegg, I came across this Samsung 50" LFD. It appears there is an "optional set back box" that would allow this particular device to act as a normal TV. Whether or not your TV is capable of this, I don't know, but it's something you may want to look into.
i wouldnt see why you couldnt make it work as a pc monitor can be used as a tv, however it most likely doesnt have a tuner so you would have to get an external one.
Plug your cable box into it using whatever connections are common between the two, viola! Although it probably does not have speakers so you'll have to use an external speaker system with it.