I'm not responsible by phone bricks of any kind, or any other damage this firmware may cause to you, to your phone or any accessories conected to your phone.
Download links and information about what is working can be found on the website (Firmware section):
Download the zip (cm-10.1-*-UNOFFICIAL-epinter-mb886.zip) and copy to your sdcard.
Boot into recovery.
Backup your firmware and data!
Install the firmware (install zip from...).
Install gapps (install zip from...).
Wipe data/cache (don't wipe if you plan to upgrade from CM10 to CM10.1)
NOTICE - I don't have a Atrix HD to know exactly how it works with this firmware, so developers needed.
People are saying this firmware is laggy, slow. Some work is needed.
EPinter - Kernel Development, Build Setup, XT925 & MB886 Support
DHacker - Kernel Development, Build Setup, XT926 Support
Hashcode - Kernel Development, Build Setup, XT926 Support
Nadlabak - Kernel Development, Build Setup, XT897 Support
Skrilax_CZ - Kernel Development, Build Setup, XT897 Support
progrockguy - For the very big patience and more than 10 tests on MB886.
Screenshots below are from XT925