see what you need to do is go down to the beach and get yourself some sand
buy a copy of 'cabela's dangerous adventures' for the xbox 360 and bury the disc in a tray of sand for exactly 14 hours and 23 minutes
while you are waiting, pour some sand into the air hole on your 360. also, remove the hard drive and put some glue on the connectors and stick sand to them
remove the disc from the sand and put it into your xbox 360 and load up the game
while the game is loading up, on your control pad you need to press X, X, B, A, RT, LT, RT
the game will stop loading and a box will appear asking if you wish to install the 'cross network compatibility package' choose 'yes'
allow the package to install, it takes approximately 3 days, during these 3 days you must run around your neighbourhood violently throwing sand at peoples windows while shouting 'WHY SO SERIO?'
you will now be able to play xbox 360 games against ps3 users online
hope this helps