Hi,

Warning: This works fine for me, but I can't guarantee it will work for 
         you. Use at your own risk!

this hack allows using either vfat or ext2/3/4 for both internal and 
external storage. It does not automatically format your filesystems, 
you have to do that yourself while the device is connected to USB.

Since this hack does not modify any of the original firmware files, 
there is a good chance it will survive firmware updates (but not 
factory resets). Otherwise, a firmware update would likely end in a 
brick or forced factory reset since the ext* filesystem would be 
considered corrupt by dosfsck.

  1. Backup all your files (rsync -a or similar)
  2. Install the attached KoboRoot.tgz (tested with H2O only)
  3. mkfs.ext4 -L KOBOeReader /dev/sdx (for internal storage)
  4. mkfs.ext4 /dev/sdy (for external storage)
  5. Restore your backup to the newly created filesystems

Note that unlike vfat, ext* does not set the executable flag 
automatically, so this may break some other mods that put binaries 
there without setting that flag explicitely.

Regards
frostschutz 
