The classic method of getting past the breakover point in tower raising or lowering is a "gin pole." You can see here a ladder being pressed into service:http://www.highhopesgardens.com/Blogphotos/2008/skystreamginladderraise.jpg
As recommended in the last post, it serves the same purpose of redirecting the vector so that you don't have the huge mechanical disadvantage of trying to hold it back before the ground crew can effectively take the weight. Of course, you have to have a line connected well up the tower, which means climbing, using a guy that you have faith in, or heaving a line with a hook to catch the tower. As said, it's nice if there's a nearby tree in which to hang a pulley. I raised forty feet of Rohn25 to a position beside a house once by putting a 4x4 inside a 2nd story window and running a line from a truck on the ground through a pulley on the 4x4 to about the middle of the tower. It came up and down nicely, with no need for anyone under it. Two people controlled lines to each side to make it thread the beam on top down between trees and fences, but the truck did all the work.
Whichever approach you use, have the ground crew reach an understanding about who with run which direction if things go wrong. Otherwise, they can be doing a Laurel and Hardy routine under the falling tower.