Once your kernel is compiled for ext3 support, you can convert your current ext2 partition to ext3 by following these simple steps:
tune2fs -j /dev/(hdx or sdx)
This will add journaling to your current partition and thus converting it to ext3. After this is done, you will need to modify your /etc/fstab to mount it as ext3 in future. I recommend you edit this and change the ext2 to auto.
