I think it was a little colder when I finally attempted mine, but I had a heat gun. It was still a giant pain in the butt. I burned myself on the heat-gun at least twice, and since the only floss I had was minty, my fingers got all minty.
To add another couple hints, don't heat the floss -- it melts or burns. Also have plenty on hand, since it breaks pretty often. If you happen to have some extra network cable sitting around, the floss-like stuff inside the cable works pretty good, too. Don't try too hard to get the letters off in one piece -- don't expect them to survive removal.
I still have to go back and clean up the leftover adhesive... yuck.