There are all kinds of ways of using that script. The details are listed in the Author's Notes section.
Just use it in place of the /whois command (you can even use it from the command line using the /who2 command).
I tried to make it foolproof, and, so far, I haven't had any problems reported since the last update (ie: Nov. 6, 2006).
If you are having trouble using my script, join #[s]cript on the irc.maximum-irc.com network and I'll be happy to assist.