I don't believe it's possible to hide the mouse cursor on a page.
I've seen my mouse cursor change on some webpages, so you might be able to
do something like that? You might create a transparent, or 1X1 cursor and
have the JS load and use that?
But as the previous poster mentioned, I don't believe any browsers support
this, even so, IMHO it would be client side scripting that would
allow/disallow this. If so, then the only thing you can do is play with
what you've got (hence my suggestion to try to bend the rules a bit).
Are you trying to mimic the Microsoft Mouse driver's Hide When Typing
feature? If you are doing that, you might be out of luck with a webpage.
You might want to consider a thick client app (VB.NET or C#, or even VB,
C++, or maybe Delphi, whatever at this layer the sky's the limit :>) where
you have control over almost everything.
HTH at least a little bit?