Instructions
Turn on your Xbox 360 and sign in tp your Xbox Live profile by pressing the center "X" button and selecting "Sign In to Profile." Press "A" after selecting your profile to sign in. Move the left analog stick up and select the "Game Marketplace" tab, then press the "A" button and select the letter "O" from the alphabetical list. Select "Optional Media Update," then press "A" to confirm your download. Do not turn off the console while the update is being applied to your Xbox 360.
Restart the Xbox 360 and sign in to your Xbox Live profile again. Connect the USB cable from your iPhone to your Xbox 360's USB port. Use the left analog stick to select "Music" and press the "A" button.
Select "Portable Device" and a list of playable AAC audio files will be displayed. Select the song you want to hear, then press "A" to begin playing the track.