• PS3 and PSP on their latest firmware
• PS3 is Wi-Fi ready (20GB owners won't get a piece of the action)
• PS3 is connected to the internet
• A Japanese PSN account

• Download the application from the Japanese PSN (5MB)
• Install and launch it from the Game menu
• Click on the adhoc button (it's the third button), and it'll start checking for a PSP
• Launch Monster Hunter Portable 2nd G and enter the Online Guild Hall (or the ad-hoc lobby of other games that might support the feature)
• Your PSP system name should be on your PS3 screen in a bit
• Exit adhoc (with the X button), click on "Start" (the first button) and you'll see different Worlds and lobbies. L1/R1 picks to pick a World, and the left stick to pick a lobby.
• Note that red tabs mean they're full, blue ones are empty
• Enter a lobby with the O button, you can view the next lobby with the directional buttons
• In the lobby move, more your cursor to a room (house icon) or player and click with the O button to view their details
• To enter a room, click on "Enter" (the second button on the pop-up), and you should be able to see other players in the room. A few seconds later, they'll be in the lobby of the game.
• You may wait until four players have joined the room or you can start a quest with the available players
• If you are having trouble finding rooms, simply create one by pointing the cursor to your name - a pop-up appears, giving you the option to either change your username or create a room. Make one then wait for people to join.

• Ad hoc Party launches on Japanese PlayStation Network
  

Via PSP Hyper