This is usually built into the "Game" column on your XMB (XrossMediaBar) once homebrew is enabled. How to Download PS3 PKG Games
Use a tool like PS3Splitter to break the PKG into smaller parts, or use FileZilla to transfer the file directly to your PS3’s internal hard drive via FTP.
PKG files are package archives that contain the game data, updates, or DLC. To install these, your console must be "jailbroken" or running a homebrew enabler to bypass the standard Sony license checks. Prerequisites for Installation
Before you start hunting for downloads, make sure you have the following: