this has been taken from http://www.tuxmagazine.com/node/1000130
it is quite easy all you have to do is use adept It should do it for you
Adept package manager, allows you to look for, download and install additional software packages. Beyond that, it worries about dependencies--that is, does your system have all the other software packages needed to make the new package work? I'm not writing a tutorial here but you basically start adept, find firefox (there is a search function), right cllick "click the "request installation" and click "apply changes" if there are other dependencies that need to be installed it will also show up in the list right click and choose the "request installtion" option and hit "apply changes"
It will probably ask you for the user password for you to continue
Having said that it is best if you do it from command line
hope this Helps,