Using an unstable package with an otherwise stable distribution

[ted <tmendum@rcn.com>]

I'd really like to use Mozilla 1.7.3 on my powerpc, but either the 
documentation I've read on how to do so is wrong or I don't understand it.

I've tried editing my /etc/apt/sources.list to include unstable, and 
then gave the command "apt-get -t unstable install mozilla" (and 
mozilla-browser) without luck.
The package can't be found.  

I tried "apt-get install mozilla-browser=1.7.3-4" which should be the 
powerpc version.  Again, the package can't be found.

I tried the debian IRC and someone suggested backport.org, but that only 
has the i386 version.  

Advice?

Thanks

Ted Mendum