Netscape Navigator 3.x for Macintosh

Start up Netscape Navigator

Select "Options"

Select "Network Preferences"

 
Find the "Proxies" tab.

Check
"Automatic Proxy Configuration"

In the URL box Enter:
http://www.hisnet.org/proxy.pac

 
Your browser is now setup to use HISnet!

Just click "OK" then exit and re-start Netscape.