I'm not sure about the m17x, but with the m9700, there was a special adapter for the tv tuner that came with the system. It has the special adapter on one end, and a regular sattelite/cable tv screw connector on the other. It's about six inches long.
It's likely if the tv out on the laptop isn't a standard, that there is an adapter. I'd contact Alienware. Some m9700 users didn't get theirs in the box, and just called Alienware and they sent them one in the mail.