Ahh, yep, I have built one (3 actually.. two courts next to each other) for my club.
Sven actually took some photos of us putting the centre wall together when we had our tournament this year. See..
http://www.underwaterhockeyworld.com...ry.php/cat/511
The idea for the soft wall comes from Durban, there in Kings Park in 96 they had a terrific wall.
For making this wall though I had the advantage that we were able to get connection points for the wall sunken into the pool bottom when it was built. That makes life a lot easier. If you want me to explain how it was made, then let me know, but if you have to put in a barrier that you have to anchor into place some other way then I haven't made one of those.
If they are building a new pool in your area it is well worth trying to get them to put something in the pool bottom for attaching a barrier. I have lived in Auckland, Invercragill and Breda, and coincidently in all three places a new pool was built while I was there. In all 3 cases it was possible to get attachments for a barrier installed.