The systems that we have locally use a special co-ax from the dish to the modem. Not sure what it is but it is definitely not RG-6 or RG-59.
The modem can be internal or external to the PC. Internals are PCI and the coax connects direct to the PCI card. Externals are stand alone boxes, the box connects to the PC or LAN switch with a Cat 5 patch cord.
I wouldn't even consider wiring anything until the satelite provider came up with some specs.