Hi Adam,
I have tried the procedure mentionned in the manual on a 1996 Golf, and it never worked either. I got pretty much the same results as you.
My feeling is this (and it's really a guess): Since it didn't work for me, for you, and others in this newsgroup, I figure it's because it can't be done on some cars. It seems the newer models' service manuals no longer mention this procedure. Maybe the VW department that takes care of the ECUs worked faster than the department that decides whether to put a plug under the back seat when it was time to eliminate this feature... (hey, the rubber floor mats for my 2001 Golf (different clips) weren't available 'till about a year after I bought the car...)
It would indeed be nice if someone out there clarified this.
best,
Erik