KSF, thanks for this great info and the pix! I was all set to approach this belt change from the bottom as I did in my old 2000 Jetta with the ALH engine, but searched and found this thread so on my 2005 with BEW it was all done from the top.
I used a 3-foot blunt pole to push the belt past the bottom (engine) pulley and slip it on. Also a slight turning by hand of the alternator pulley was needed to get the belt to finally seat.
Also, I didn't have a 16mm wrench but an adjustable wrench worked just fine to move the tensioner, and a drill bit (point goes in the hole) was used to keep it in place.