Hi ulno,
I created the bootable CF by imitating this thread:
http://forum.irexnet.com/viewtopic.p...r=asc&start=15
mke2fs is the first step to create a bootable CF. After created, I used dd to backup the whole CF as an image. After used, the bootable CF can't be used again, so I have to "dd" from the backup image to CF.