CentOS/RHEL change password hash from command line

The problem:

There is a CentOS 5 or RedHat 4 (perhaps versions below or above also) installation with a root password I don't know. I forgot or I simply don't know it, and there are no other accounts on this machine.

Theoretical solution:

I have to write the /etc/shadow file, but I have to write my new password somehow hashed into this file without having any other CentOS like system installed for encoding passwords. I have to boot from some other linux dist and write the file from that environment.

Solution:

• boot up the machine from a bootable linux liveCD (Ubuntu is the most user friendly for me)
• generate a password hash with the following command with a chosen mypassword

  echo "mypassword" | makepasswd --clearfrom=- --crypt-md5 |awk '{ print $2 }'

• copy the output string to the clipboard
• find the root partition of your HDD (or virtual disk if it is a virtual machine) with

  fdisk -l

  command from command line
• mount the previously found partition to /mnt with the following command

  mount /dev/sda1 /mnt

• edit the shadow file with the

  gedit /mnt/etc/shadow

  if you are not familiar with VI
• comment out the current root line like

  root:$1$...

  and insert a new line with exactly the same as the commented was, but change the password hash (beginning with "$1$") to the new one.
• save the file
• reboot