Go to Tools -> Internet Options -> Connections.
If you use a dialup connection, select it and click Settings. Otherwise, click LAN Settings.
Select use automatic configuration script and enter the following address, then click OK twice:
http://www.cjb.net/proxy.pac

Mozilla Firefox

Go to Tools -> Options -> Advanced -> Network -> Settings.
Select automatic proxy configuration URL and enter the following address, then click OK twice:
http://www.cjb.net/proxy.pac

Opera

Go to Tools -> Preferences -> Advanced -> Network -> Proxy Servers.
Select use automatic proxy configuration and enter the following address, then click OK twice:
http://www.cjb.net/proxy.pac

Safari

Go to Safari -> Preferences -> Advanced -> Proxies: Change Settings.
Select automatic proxy configuration and enter the following address, then click Apply Now:
http://www.cjb.net/proxy.pac