It seems i've posted without doing necessery research.

http://wiki.maemo.org/Mer/Releases/0.17 (testing one)
http://wiki.maemo.org/Mer/Releases/0.16 (stable one)

In those links are prebuilt archives for n8x0 devices. Those archives are just root file system for mer. I have no idea how to ably that to my device. Can i just extract the filesystem to n810 and it next time boot mer? Or do i need to use utility like flasher?