http://forum.tvfool.com/showthread.php?t=901
If you are interested in what the NEC calls for, it allows you to bring the grounding conductors for an antenna system into the building as far as five feet. That is an allowance for situations such as yours, where there is no ground rod outside the building.
Ideally, you would run a #10 or larger copper wire from the mast, to the electrical service ground... in as direct a path as possible, avoiding sharp bends. All outside the building.
Ideally, you would run the antenna lead/coax to a block such as the one you linked to. That block would be located as close to the electrical service ground as is practical. The ground block would be connected to the electrical service ground with a #14 or larger copper wire, as directly as possible and with no sharp bends. All outside the building.
Best practice would keep the mast and coax ground separate until they come together at the electrical service ground.
You can add a ground rod... if you choose to, it must be bonded to the existing electrical service ground with a #6 or larger copper wire. I chose to do this because my mast is some distance from my electrical service.
A beer or two invested in a local electrician friend may pay dividends... in advise or help.