Instructions
Turn on the Xbox 360.
Turn on the wireless "Guitar Hero" controller that you want to synchronize with the Xbox 360.
Press and release the "sync" button on the Xbox 360. The "sync" button is a small circular button in between the Xbox 360 power button and the memory card inputs.
Press the "sync" button on the wireless "Guitar Hero" guitar. This button is located on the rim of the guitar near the guitar's power button. The guitar will immediately synchronize with the Xbox 360, and you will be able to use the controller within a few moments.