Instructions
Insert the flash drive in an available USB slot in the front of your Xbox 360 console.
Press the "Guide" button on the front of your Xbox 360 controller. This button is in the shape of silver X, located in-between the Start and Back buttons.
Select "Settings," "System Settings" and then "Memory."
Select the "USB Storage Device" option in the Storage Devices window.
Select "Customize" or "Configure Now." Customize enables you to set aside only a portion of the flash drive for Xbox 360 usage, while Configure Now will erase all content on the flash drive and use all available memory for Xbox 360 usage. Once configured, you can now use the flash drive as a memory unit.
Select "USB Storage Device" when prompted, such as when downloading a demo or saving a game, to save the data to your flash drive.