[porg]

Your system disk broke, you want to restore it, and have your backup on a sparseimage on a disk other than HFS+ or on a network volume (samba, ftp) , thus no option to boot from this backup.

A superduper boot CD could fill the missing gap.

Once booted one could restore from the diskimage to the reformated/replaced harddisk (assumed that disk utility is on this Boot CD)