1. Make sure your OS has the packages needed:
http://www.mozilla.com/en-US/firefox/system-requirements.html

2. https://support.mozilla.com/en-US/kb/Installing+Firefox+on+Linux

There are no requirements listed for Solaris on the link above.

Are the Solaris requirements and instructions the same as Linux?

What does *Linux* have to do with the question I asked above?

I'm trying to install on Solaris 10, not Linux. I find no packages and no running insallation script. How am I supposed to even try to install?

This is what I did to install Firefox 3.6.12 on Oracle Solaris 10. I found that Firefox 3.5.9 was already installed and there exists /usr/bin/firefox and /usr/lib/firefox. Turns out that /usr/bin/firefox is a symlink to ../lib/firefox/firefox so all you really have to do is remove the old /usr/lib/firefox and extract the new tarball to /usr/lib.

These are the steps I followed. I did this all as root.

bash-3.00# uname -a

SunOS unknown 5.10 Generic_142910-17 i86pc i386 i86pc

I made a backup of the existing install in case I messed something up.

bash-3.00# cur_ver=`grep '^moz_libdir' /usr/bin/firefox | cut -d - -f 2`

bash-3.00# ln -sf /usr/lib/firefox-${cur_ver} /usr/bin/firefox-${cur_ver}

bash-3.00# mv /usr/lib/firefox /usr/lib/firefox-${cur_ver}

Then I cd to the directory where I extracted the tarball.

bash-3.00# ls

firefox

firefox-3.6.12.en-US.solaris-10-fcs-i386.tar.bz2

bash-3.00# find firefox -print | cpio -dp /usr/lib

That's it. I started Firefox from the desktop Launch menu item. Once it came up, I checked that it had my old history, which it did, so I assume my user profile was upgraded okay.

You could have just as easily extracted the tarball directly to /usr/lib (assuming the tarball is in the root directory).

bash-3.00# cd /usr/lib

bash-3.00# rm -rf firefox

bash-3.00# bzip2 -cd /firefox-3.6.12.en-US.solaris-10-fcs-i386.tar.bz2 | tar xf -