I made a mistake (late) last night when saying FW = kernel.
It should be kernel+rootfs.

Perhaps this is also worth trying:
http://wiki.meego.com/ARM/N900/MMC
(READ first and follow the steps exactly)

If you can boot MeeGo form microSD, you can try some repair operations on the eMMC, such as fsck and repartitioning. Then you can try flashing again.

Once my N900 refused to boot. I ran MeeGo from card and copied all the important stuff in the eMMC, and then flashed it.

And it doesn't hurt even if you fail to set up MeeGO because everything is done on the microSD card and does not mess with the internal memory.