Joseph Herlant
version 1.0.0, 2014-07-05 : Initial version
  1. Add "selinux=0 init=/bin/sh" at the end of the "kernel" line in grub

  2. Check if /var/lock is writable via touch /var/lock/toto

  3. If not, remount the filesystem in writable mode via mount -o rw,remount / (if your /var is on /…)

  4. Check which packages are to be reinstalled via yum -C provides /etc/init*

  5. Mount installation CD via mount -r -t iso9660 /dev/sr0 /mnt

  6. Reinstall upstart and initscripts via rpm -Uv --force --noscripts /mnt/Packages/upstart*.rpm /mnt/Packages/initscripts*.rpm

  7. Verify there is no more missing files from the packages via rpm -V initscripts and rpm -V upstart and rpm -Vf /etc/init

  8. Unmount CD, eject disk and reboot (unsing reboot -f)

Note
You can also boot from the cdrom rescue mode.