Squid - startpage?

[Hermann-Josef Beckers]

Does anyone know a way to send a generic startpage after/before users  
authenticate themselves to squid? We would like to remind our users of 
"correct" behaviour (no "bad/bed pages", no private surfing) when connecting 
to the internet. 

The home/start-buttons of the browser(s) are no alternative as they are 
reserved for our intranet. 

Any hints? Do I have to use a "transparent proxy"? 

TIA
hjb