For this you will need:
1) Determine the game id of the game you wish to update. This is either on the bottom of the spine of the case or can be found at www.gamefaqs.com in the data section of the game's page.
2) Open Awesome Update Finder, enter the game id and search for updates.
3) Copy the download link, and open it up in a browser. Save the file.
4) Put the pkg file on the root of your flash drive, plug it into your PS3
5) Go to the install package files option on your PS3, install the patch.
6) Success! Your game has now been patched.