Instructions
Select "PlayStation Store" from the "PlayStation Network" tab on your PlayStation 3's main menu.
Select "View All By Title," followed by "L" and "LittleBigPlanet PSP."
Select the costume pack you wish to download. When the download is complete, return to the main menu of the PlayStation 3.
Connect your PSP to the PlayStation 3 using the PSP USB cable. The PSP automatically enters USB Mode.
Navigate to the "Game" menu on the PlayStation 3 and highlight the downloaded "LittleBigPlanet PSP" costume pack.
Press the "Triangle" button on the PlayStation 3 controller.
Select "Copy" followed by "Yes." The costume pack is copied from your PlayStation 3 to your PSP.