I did this a long time ago. Currently my N810 has stock diablo on it as it got shelved for sometime.

You can read what I was able to accomplish using Mer as a base a while go, however:
here (way outdated setup procedures)
here
here
and here

I have not tried the newer Mer's yet. Don't know if anything significant has changed. Theoretically, as long as it's still using a Debian/Ubuntu base.. the same thing could be accomplished still by removing and adding the appropriate packages as I did.

There also existed several threads here on t.m.o on getting LXDE and GDM/Gnome setup and configured on the N810.