After trying unsuccessfully to configure squid in gedit, I gave webmin a try, and it worked great. Here are step-by-step instructions: http://rootzone.net/setting-squid-pr...ver-on-webmin/

Note: it's very important to have your port forwarding set up correctly.

Note 2: If you use autocomplete to enter your username at the prompt, be sure to delete the space that shows up automatically. That had me stumpped for close to 15 minutes.