first problem is that the nokias use the TI omap processor, so there are binary compatibility issues, which means you're going to have to build from source. You might find get better compatibility with the 770 as that has an older processor than the 800 and 810.
second problem is not all of maemo/hildon is open source, but you could probably build most of the software, but not sure what would be missing. your best bet would be to ask on internettablettalk forum (or search there) to find out whether you could build the complete system image from source, minus kernel (use the one from angstrom or debian) or at least enough to make it work!