i was able to upgrade my firefox 3.0.xx to 3.5 a couple weeks ago with the help of jun auza (thanks dude). i opted to follow his second option of installing ff 3.5 with one command. a few days ago i found out that firefox 3.5.2 was released. to upgrade to the latest i looked for the package for my distro from the mozilla releases page. then on the terminal i issued a slightly modified command from jun’s:
wget -O - http://releases.mozilla.org/pub/mozilla.org/firefox/releases/3.5.2/linux-i686/en-US/firefox-3.5.2.tar.bz2 | tar xj -C ~
this should work for future releases. just check the full url of the release first from mozilla and modify the command as needed.
important note: this worked for me. it may not work for you. the risk is yours.