still think the easiest option would be to pull Meego apart to see how closed source components were implemented, then start from scratch. sounds like a lot but would simplify the task of having to work round on going issues with out of date/closed source apps. would also free project from nokia and make it available for other devices.

build an up to date base/core from scratch or use debian arm/embedded. advantage of second is core is updated for you by someone else.
build up to date kernel for updated drivers. lots of rx-51 commits made it into mainline iirc. or just rebuild meego kernel.
replace non gui closed source apps. replace telephony stack with ofono.

then test operation from cli. one done, start on gui.

rebuild hildon source and dependancies.
replace closed source apps with those from cssu.