Netscape Navigator 4.x for Macintosh

Start up Netscape Navigator

Select "Edit"

Select "Preferences"

 
Find "Proxies" within the "Advanced" preferences section

Check
"Automatic proxy configuration"

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

Select "Reload"

 
Your browser is now setup to use HISnet!

Just click "OK"