Went through the same search by making phone calls and reading manuals but to no avail. Others recommended looking in ceiling light fixtures and air conditioning covers and still no cable.
Here's the bottom line. If you're looking at adding a high definition satellite dish, you'll need at least the number of coax cables that you have TV's, which in most cases are (2), maybe (3) if you have a bay TV. You'll also need a data cable from the dish to the controller for the Directv Travl'er, not sure about the other companies like Dish.
We found a path, approx. (4") running from the AC unit to the front coach cabinet area. Drilled the center roof where this trough was just below and ran the cables.
Hope this helps
2008 Itasca Meridian
2010 Ford Sport Trac