Why Firefox 19? The versions currently supported by Mozilla are Firefox ESR 24 and Firefox 26. ESR is Extended Support Release. ESR releases are what are currently provided in SLED.
SLED SP2 will go End Of Life very soon. If you update to SP3 you will get Firefox 24 ESR along with it.
The version of Firefox currently provided for SP2 is 17 ESR. Assuming your machine is properly registered and has access to update repos you should get 17ESR just by installing all outstanding updates. Have you not been installing updates?
You can download a .tar.bz2 of Firefox 19 and every other version from ftp://ftp.mozilla.org/pub/firefox/releases/ you simply unpack it and then run it.