You can download and install the latest rpm's. This worked for me in 9.1 Pro, but YMMV.
I had been using YOU to do security updates on the original installation of firefox. I also noticed that all of the updated files were in the "/opt/MozillaFirefox" directory. Well, when I decided to take advantage of the new 184.108.40.206 version, I used advice that I had learned some time ago, and deleted the old rpms using YaST before installing the new ones. The newly installed files ended up in "/usr/lib/firefox", which was dictated by the new firefox rpm and its install routine, while the original "bin", and "installed-chrome.d" directories were removed from the "/opt/MozillaFirefox" directory, due to the deletion of the old rpm's in YaST. The "lib" directory remained, but with only a few files. I checked my link in the window manager that I use to access both kde and gnome programs, and also checked it while in kde itself, and they all point to the new install which is running great so far. You can download themes and "skin" it at will. I mention this so that you have some idea of what may happen. If you have been using "tar" files to install firefox, I'm not sure what effect, if any, doing the rpm install may have. Someone else may be able to address that.
1.) Using the links below, download the four firefox/thunderbird rpm's into a new directory (maybe called firefox_rpms) in your "home" directory. I included a mirror in case the other was slow.
2.) Go into YaST>Software>Install/Remove Software, use the "search" feature to find the MozillaFirefox and MozillaThunderbird (if you have it) packages and any associated "-translations" packages, and let YaST delete them. I close YaST at this point. No sense in tempting fate.
3.) Using "FileManager SuperUser Mode" in kde, go to the directory where the new rpm's are, and right-click one of them. You may be able to highlight all of them by holding down the "shift" key and left-clicking on one of them, and then have YaST install them all at once, but I never tried it.
4.) Select "Actions", then select "Install with YaST". Repeat steps (3) and (4) for each rpm. I didn't install thunderbird, but it would have ended up in "/usr/bin" and "/usr/lib". You can "look inside" any rpm while in konqueror, either as a regular user, or as root, by right-clicking on it and selecting "Preview in KRPMView". Then select the "Files" tab to see where the files will be going.
It will probably show in the kmenu, but I'm not sure.
One other thing - the YOU security patches will no longer work in this case. You will just go thru the same process for each version of firefox that becomes available for 9.1.
Hope this works for you - good luck !