UPDATE: It has been confirmed that this method does work on ATT Gingerbread version 2.3.6 4.5.141. PLEASE follow all instructions and do not panic when device states “unable to boot” – Thanks to @soldieronarms for trying this out!
UPDATE: The megaupload link on the instructions do not work anymore. Here is an alternative link:
This is where I got all the info and download from:
Motorola Atrix Drivers: (Click on download Motorola Drivers)
USB and PC Charging Drivers – Motorola Mobility, Inc. USA