My suggestion is to convert Clonezilla disk image into a virtual machine which you can launch the virtual machine to retrieve the Office 2007 licence code.
For details, please see the link below.
http://www.ibm.com/developerworks/linux/library/l-clonezilla/I do not suggest you to take ownership of the folder \Windows\System32\Config in your cloned external drive unless you make a backup of the drive image first.