Ok this will probably be one of the shortest tutorials on ebay because it's so simple. If you want to play wireless multiplayer ad hoc with one of your friends and you only have 1 copy of the game, have no fear PSP-Hacks.com is here. Below are the steps to playing multiplayer PSP with just one copy of the game.

1. Start up an ad hoc multiplayer game and set the time for unlimited.
2. On the first PSP Eject the UMD disc and choose NO when it asks if you would like to quit.
3. On the first PSP Put the UMD in another PSP and start multiplayer gaming with your friends!

--Reapeat previous previous 2 steps for as many players as you want in the game--