[squid-users] Redirecting no proxy users to a PAC file automatically

Hi,
I'm trying to do this ideal configuration:

- 1 proxy server in the intranet
- users that does not use the proxy for browsing, land in a local
website with
  a link to an automatic proxy configuration script, PAC, .js, ...
- then, if the user use the proxy, he browse the Internet normally

I have seen in some ISP that you enter "www.google.com" and you end up
landing in an ISP page saying that you are over quota, didn't pay, etc,etc

How I can redirect any URL to a website?
And, how can I create a PAC file so that the user click on the URL and
his browser configures itself to use the proxy?

Many thanks
Oliver

-- 
Oliver Schulze L.   | Get my e-mail after a captcha in:
Asuncion - Paraguay | http://tinymailto.com/oliver