Mount a DMG under Linux
From Stack Overflow
Make sure the proper things are installed
sudo apt-get install hfsplus hfsutils hfsprogs libhfsp0
Make sure the proper modules are loaded
sudo modprobe hfs sudo modprobe hfsplus
sudo mount -thfsplus -oloop /path/to/file.dmg /path/to/mount
Note that this doesn't work with all DMG files for some reason. You may have to bunzip first if they're compressed.