I built a new house 4 years ago, and did all the coax/Cat5 wiring myself. I have a "network room" in the basement, where all the drops in all rooms terminate - a "star" topology. The 2 coax cables coming in from my DishPro sat dish are then routed through the house to the room with my 722 unit, and then 1 more coax comes back down to the network room (so - 3 total coax lines to the room with the 722 unit), where it is attached to a multi-way splitter, which goes to many rooms - I can switch cables from any room around. Same idea if you had more tuners (and, if you have the RF remotes for the additional single-tuner units, put the tuner(s) in the network room, run the output to a splitter and have that go to multiple rooms at once).
When the Dish installers come to install the new DishPro/Plus, they will provide the (2 runs for my 722) coax from the DishPro itself to wherever in your house (at least that's what they did for me) as part of the install. You shouldn't need to have your wiring company pre-place the coax outside of your house. If you're unsure, call Dish or a local installer and ask what is provided in the standard install package.