The new server side of the New Animation Overrider functions is scheduled to roll out to the Blue Steel and Le Tigre Release Wednesday. The only viewer that has added the AO functions, AFAIK, is Niran’s Beta 2.1.6 (2600).
The functions will only work if you are in a Blue Steel or Le Tigre channel region.
As far as I know Niran’s viewer does not have a built in AO. He only added the functions to the script editor. So, you get syntax highlighting. But, you can use the viewer to write test scripts. You just have to be in a Blue Steel or Le Tigre region.