Instructions
Turn on your PlayStation 3. Open the PlayStation Store from the "Network" menu on the console's home screen.
Select "Search" and search for "PS2 System Data." Select the "Download" link on the "PS2 System Data" product page to download the file to the PS3's hard drive.
Exit the PlayStation Store, and return to the system's home screen.
Select "Game." Under this heading, you will see an icon representing the PS2 System Data file. It will have a circle around it, indicating that the file has not yet been installed. Select it with the "X" button to install it on the PS3. Now, whenever you insert a game in your PS3 that requires the PS2 hard drive add-on, it will play just as it would on the PS2.