The simplest method is copying the PKG files to the root of the ISO.
- Once you mount the ISO, you can go directly to Package Manager to install the DLC/update patch packages.
Another easy method is using my Create PS3_EXTRA found in my
PS3 Tools Collection
Put the PKG files (updates, dlc, fixed, etc} in PS3 UPDATE folder or in the root folder of the game, run the tool, select the Games folder and press the button to create the extra folder in the selected games.
Your game mounts a second disc. You can make your DLCs look like this
View attachment 42752