If it was an ISO method, this is what would have to be done.
You would download the ISO and obtain:
patch_mp.ff
code_post
Do a backup, and rename the patch_mp.ff to "archivexxxx.dat," the code_post to "archivexxxxx.dat," then restore the backup.
This would have worked if the PS3 was an older version, but this was said to be patched in version 2.50.