I actually think this script belongs to Willam van Weelden.
As for grainge.org licensing, you're best of asking Peter.
I also have a toolbarscript for WebHelp and it might just be the same as the one on Peter's site. (I couldn't find it right away on grainge.org, so I'm not sure.) If you use the script from WebHelp (Pro) Toolbar scripts | WvanWeelden.eu, there's no licensing required. Just leave the copyright notices in the top of the script.