I can't walk on my roof, it's too steep. but I had to get a rope between the vents on my chimney. So I set up a ladder, and grabbed 20 feet of pvc pipe. attached the end of the rope to the end of the pipe, climbed the ladder and looped the rope over the chimney.
only took me 4 tries.
Once that was done, it was just a matter of attaching the rope and pulling hard.