If you want to modify the first disk or simply spy my startup secrets you can extract the ext2 filesystem entering:
dd if=bootdisk.img of=rootdisk.gz bs=1k skip=600
gzip -d rootdisk.gz
mount -t ext2 rootdisk /mnt/alien -o loop
You will have the rootdisk of the first disk mounted into /mnt/alien
For the addon disk it's even simpler, it's a tar.bz2 !
For adding something (ex: a network card module) in the second disk you only need to do something like:
bzip2 -dc disk2.img |tar -x
Make changes then recompress it:
tar cvf - mininux |bzip2 -9 > disk2.img
Verify the disk is under 1440ko !
WARNING!
If you manage installing the addon disk you must type 'addon' in the Mininux' shell.
This files and my work is uder GNU Library General Public Licence, read it!