Impossible? No- just a lot of work. Since I’m not running a kernel with ext4 support anymore, I had to do this to get my home partition into ext3:
- boot into a livecd with ext4 support
- image the partition to a firewire drive using sudo dd if=/dev/[partition] of=/media/firewire-hd/home_5_16_2009.img
- in the Partition Editor (gparted) reformat the partition as ext3
- run rsync -vrlpogt /source /destination to copy my files from the image
- note that you still may need to chown -R your home directory to the appropriate user and group name if you see 1000 as your group name when you do an ls -la in your new ext3 home directory.
Yes- it is indeed cheating.