On device type in terminal or through ssh:

Password for devel-su you can set in Settings -> Developer Tools -> Remote connection password
devel-su ssu ar mister http://repo.merproject.org/obs/home:/mister/latest_armv7hl/ 
devel-su zypper ref mister
devel-su zypper in libpurple libpurple-plugin-facebook

Ensure you have enabled nodevel repo in warehouse.
devel-su zypper in haze-accounts-extensions-facebookmessenger
it will throw error. Use option 2 aka
"Solution 2: break haze-accounts-extensions-facebookmessenger-0.4-1.noarch by ignoring some of its dependencies"

There you go! Add facebook messenger account and have fun until i make my messenger. You have to login using phone number in order to have peoples names. If it's not working then reboot phone  several times. There is no "Set message as read as soon as it arrives" problem ;) However it's not set as read until you answer :)