osx .dmg files can be easily converted to raw disk dumps (for use with the venerable dd) thusly:
hdiutil convert -format UDTO -o new.dd original.dmg
Then you can ‘burn’ the image onto a thumbdrive or the like:
dd if=./new.dd of=/dev/disk2 bs=2m
Note that if you get the output file parameter wrong, you run the risk of overwriting something you might not want to, like your boot disk.
