The easiest way to install Firefox 1.0 might be klik://firefox (you need the klik client which you can install from http://klik.berlios.de/ - Kanotix has it by default).

Since klik installs everything into an application directory inside your home directory, it will even run from Live CD and it won't mess with your system. (If you don't want it anymore, simply remove the firefox direcory from your home.)

Greetings,
probono