you can follow the following procedure to unlock bootloader for Razr developer edition and Xoom:
Agree to the terms and conditions as outlined in the Motorola Unlockable Bootloader Legal Agreement.
- Take full backup and make sure the device's battery is fully charged
Install the Android SDK on your computer.
- Power off your device, while holding the volume down button, press the power button for about 1 second and release the power button. Once you get AP Flashboot Flash mode, release the volume down button.
Connect your device to PC and install Motorola Device Drivers.
Run 'fastboot oem unlock' from your PC's command line interface to activate the unlocking process.
- On your device, scroll down through the warning by using the volume DOWN button. Highlight ‘unlock’ using the volume DOWN key. Select ‘unlock’ (or ‘cancel’) using the volume UP key. The device will reboot, rebuild, and return to the fastboot screen. The fastboot screen will display the device as unlocked.