I have an Atrix 4g that was about to be retired or sold, and decided to instead make it an android project to learn about modding and possibly make something useful out of an old device.
After combing the forums on this site and others, realized there was some risk involved of a hard brick, but since this is not my main phone anymore, I wasnt too worried about. I'll share the results...
The phone was running gingerbread 2.3.6, ATT 4.5.145 build
[notice: I have removed the actual instructions]
I hope this helps users out there with old Atrix 4g's considering giving them new life. I'm going to try CM 10.x soon to see how jellybean runs on the Atrix 4g. Wish me luck!
Vengaence