Doing some research, it became apparent that G4L uses Gnu DD behind the scenes to create the disk image. Basically G4L is a wrapper around dd to make it easier to perform networked backups. This was great as it meant that I did not have to deal with proprietery or weird formats.
Recently a colleague of mine used G4L to backup his disk. G4L is nice and handy if you want to backup an entire disk in zipped (bz2) format and ship it off to an ftp server for backup. We now needed to recover some files off that backup. The issue is all of our machines are identical, and since the backup was a lowlevel image of the entire disk, unzipping the img would not be possible. This post describes the steps I took to manage to mount partitions out of the bzipped image.