How about downloading source code from mercurial repositories and cross-compiling it for arm?
This might not be a good idea as to your requirements but it can be an option at the last.
Kindly let me know the solution for this. As I am also looking to install Firefox/Mozilla on to my SABRE Tablet. Please let me know where to get the source code for this.
You should place the source code into /opt/freescale/packages
and place the spec file into <ltib>/dist/lfs-5.1/FIREFOX/firefox.spec (or something like that)
You can also use ./ltib -m shell go to firefox dir and use make or configure using the environment variable from LTIB