Its in the zip file linked to at the top of the guide "3.02 OE-A Pack".
You just need to copy the official sony 3.02 and 1.5 firmware update files into the same folder, renaming them as shown (renaming the eboot.pbp you extract from each updates zip file, not the zip file renamed).
Once your at 3.02oe-a as this guide shows, you can also update to the latest version of the custom firmware,
3.03OE-A'