Things You'll Need
Instructions
Turn the Xbox 360 off. Insert the USB flash drive into any available USB port on the Xbox 360. Turn the Xbox on. If you already have the update installed, skip to step 2. Otherwise, use your Xbox LIVE profile to connect to Xbox LIVE and ensure that you have the latest update. When prompted, wait for the Xbox to restart.
Go to the "My Xbox" menu. Select "System Settings," then "Memory." A list of available storage devices will be displayed.
Choose "USB Storage Device," then "Configure Now." When asked to confirm, select "Yes." The USB flash drive will be formatted and tested. After the test is complete, the USB flash drive will be listed as a "Memory Unit" in the storage device list.