From MEPIS Documentation Wiki
Firefox is an open-source browser, and as such it is much easier to write extensions (programs) for it than a closed-source browser. Under the Tools menu --> Extensions --> Get More Extensions, check through the privacy section. There are several good ones here, Anonymouser is OK, if you can live with the banner flash ad in the middle of the page. Anonymization Toolbar is better. And FoxTor. While you are there in extensions get Torbutton and install it.
The real program to install is Tor.
add the line at the very top of the file--and don't forget to add the dot at the end.
forward-socks4a / 127.0.0.1:9050 .
you will need to comment out these three lines by inserting a # before each:
logfile logfile jarfile jarfile debug 1 # show each GET/POST/CONNECT request
4. Restart Firefox for the changes to take effect. Torbutton will be used to enable/disable Tor surfing on the bottom of Firefox.
5. You need to test your IP address number. Make sure to delete all your cookies first.
This site does a good job in telling you your IP address, web browser, and OS used. Opera gave it the least info in my test. You won't be able to test it in two different tabs without probably getting the same IP results.