[Zope] Handle "Unauthorized" error message

[Paolo Dina]

Hi guys.
I have a part of my site which is protected by password.
All works fine and this is really a simple task with Zope(v.2.5.1), 
but now, how to prevent the unauthorized user to read the error message:

Site Error
An error was encountered while publishing this resource.
Unauthorized
You are not authorized to access this resource.
blahblah

How do i replace that with something more friendly?(a redirect to an 
error page would be great too).

Thanks
Paolo Dina

P.S.: i know that Cookie Crumbler makes something similar, but i won't 
use it in my site.