########################################################################
# Here is the genisoimage command line I used to patch a debian        #
# installation CD to alter its initrd.  The isolinux.cfg was patched   #
# to specify the alternative initrd location.  The kernel was not      #
# altered from the version on the CD, but that can be done in the same #
# way.                                                                 #
#                                                                      #
# (Alternatively to -graft-points, bind mounts could be used.)         #
########################################################################

# This step is necessary because isolinux.bin has to be writable,
# because genisoimage modifies it on-disk.
sudo mount --bind isolinux.tmp.Z3Va9k \
          iso-mnt/boot/isolinux/isolinux.bin

genisoimage -o samizdat.iso \
          -b boot/isolinux/isolinux.bin \
          -c boot/isolinux/boot.cat \
          -no-emul-boot -boot-load-size 4 -boot-info-table \
          -iso-level 4 \
          -V 'Samizdat uYr7YmecI0VeCJteX0imQfo'  \
          -graft-points \
          samizdat/boot/initrd.gz=initrd.cpio.gz \
          boot/isolinux/isolinux.cfg=isolinux.cfg \
          iso-mnt

########################################################################
# Here is a parameterized version (untested):                          #
########################################################################

INPUT=./iso-mnt
OUTPUT=samizdat.iso
VOLID='Samizdat uYr7YmecI0VeCJteX0imQfo'
GRAFTS='samizdat/boot/initrd.gz=initrd.cpio.gz boot/isolinux/isolinux.cfg=isolinux.cfg'

genisoimage -o "$OUTPUT" \
          -b boot/isolinux/isolinux.bin \
          -c boot/isolinux/boot.cat \
          -no-emul-boot -boot-load-size 4 -boot-info-table \
          -iso-level 4 \
          -V "$VOLID"  \
          -graft-points $GRAFTS
          "$INPUT"