How to install Firefox themes on Solaris?

I am running Firefox PR1 on a Solaris Sparc system and I can't get
themes to install.

When I click on a link to a theme jar file the only option I get is to
save it to disk.  So I save it to disk!  :-)

I have tried the javascript installer at
    http://texturizer.net/firefox/themes/#install
but that appears to do nothing.  I've even set up to allow
textrizer.net to install software on my system, still nothing.

I've also tried to drag&drop the jar file into the themes window,
nothing.

I'd really much prefer a 'command line' method to do it.  Can I just
unpack the jar file and stick the bits somewhere in my Firefox
configuration?

-- 
Chris Green