Thanks guys.

i have now manged to get MSN to connect on both N800 and N810.

i could do it all from app manager, enabling extras-devel, then changing to "red pill". Red Pill can break your tablet if not careful!

i needed to update telepathy-haze to version 0.2.1-2, and libpurple0 to 2.6.3-6nix0, and then reboot manually once app manager had completed updating.