WARNING: This is NOT for the Bell Atrix. Always backup your data and assume the risks with doing this to your device.
Downloads
ROM:
http://bandbinnovations.com/xda/gingerblur-4-5.zip
Instructions I used:
http://briefmobile.com/atrix-4g-rom-installation-guide
What Gingerblur is and review:
http://gadgetu.net/hands-on-motorola-atrix-4g-with-gingerblur-rom/