I tried this glitch and out of 25 times i tried it, i got it once and died 3 time
However, i found an easier way to do this. You need a Awful Layton (upgraded crossbow), or monkey bombs. You basically get a horde of 15-20 zombies and shoot the awful layton in front of the stairs (or throw monkey bomb in front of stairs), and jump on them quickly before the effect of the crossbow/monkey bomb wears off.
It is still the hardest glitch i have done to date.
Other forums call this method "zombie surfing" and has been used to get out of the map in der riese? I am not sure of the validity of that, but i will try it next time i play zombies on Der Riese.