Cable From Above
Assuming that you have cut the hole for the telecommunications outlet, you can simply drop the cable into the wall from above and fish it out.
This requires that you have the cable positioned above the wall frame and the location where the telecommunications is located.
When you are pulling cable up from the room into the attic, a person in the above the wall feeds a thin wire (aka fish wire) down the opening to the telecommunications outlet hole.
The person at the bottom tapes the networking cable to the end of the fish wire.
The person above the wall then pulls the cable up into the ceiling.