This went real smoothly for me except the part where it says:
"Locate the text string "URL/TO//sproxy.pl" and modify it to the location of your
UBBCGI directory.
Locate the text string "URL/TO/initspell.htm" and modify it to the location of
your NONCGI directory."
It isn't clear whether it wants an absolute path, a trailing slash, or what. If fact it says "location of the directory" when it actually wants the location to the file.
I would change this to:
"Locate the text string "http://www.yoursite.com/UBB/initspell.htm" and modify it to the location of
your NONCGI directory."
or somthing like that where it is clear what kind of path you are looking for. It would save a lot of trial and error.
Otherwise, it works great and is somthing the users have been screaming for, so props for coming up with this valuable hack!!