I tried. By while partitioning I forgot about the hardcoded partition ids in Maemo, which rendered Maemo unbootable.

Is there any other way to fix it than by undoing the partitioning and reinstalling Debian?

My partitioning:

/dev/mmcblk0p1
/dev/mmcblk0p4
/dev/mmcblk0p2
/dev/mmcblk0p3

I'd need to move p4 to the end of the disk