You purchase them or download free items from the Playstation Store
Buy the metal gear solid add on content from playstation store and you'll get it in the levels
If you mean "install" by connecting to a PC by usb, you connect it to your PC and run add hardware or let it detect your PSP and your computers should already have the drivers or you can download them for free.
If It Is For Psp I Dunno But For Ps3 You Go To The Store And Click Game Add ons And Then Click l The Find Little Big Planet Then You Go On To Buy Them.Joel
You cant :/ but when littlebigplanet 2 comes out you will be able to :)
music box
you have to have custom firmware and use the umd usb connection then add it in the map foldersYou can also do it this way... You need the latest PSP firmware 5.51 here www.us.playstation.com/PSP/Downloads/systemupdate and go to the playstation store on your PSP.No Iddiot youadd-ons are official while Custom Firmware is not you put it in ms0:\psp\game Directory
You can download a DLC or add on to a game and use it to play with the UMD game
First go the the game then click triangle and several options should come up. Go to the one that says "update" The click X. Then from there it should all be pretty straight forward.
No the game of the year is better because it comes with free bonus add ons
you add a scoreboard from your tools bag
No,there is nothing like zombie cheat not in PSP and not in PC.But you can add a zombie mod in GTA VC PC.
You can add keys, but in some levels you can collect a key which unlocks an extra level.