There's been some discussion of this on other lists. From what I've read, the closeups of the "tower climbers" were done on a sound stage in Hollywood, in front of a green screen, with the actors on a short section of "tower".
The long shots were probably real tower guys, dressed like the actors, and that is a real tower somewhere in the DFW area.
Only in Hollywood would you have a couple of guys climb a tower with no antenna or much of anything else on it, carrying no visible tools, just to swing around on their harness and drink a pop....