Instructions
Press the sync button on the Xbox 360 console. This is the small circle button on the front of the console next to the memory card slots.
Press the Xbox button on the Rock Band guitar controller. This is the gray button with a green "X" on the front of the controller. The green lights on the console and controller will flash for a few seconds. The guitar controller will be synced to the console when the lights stop flashing. The guitar controller must be synced to the console in order to function.
Locate the headset port on the guitar controller. It is located on the side edge of the controller. This is a small port that is easy to overlook. It is located approximately in the same location as the cable jack on an actual electric guitar.
Insert the plug from the headset microphone into the port on the Rock Band guitar controller. The microphone is now set up and ready for use.