LiveCD ISO to a bootable USB stick:
$ mount *\\ to see current drives
$ diskutil umountDisk /dev/diskN
$ sudo dd if=/path/to/downloaded.iso of=/dev/diskN bs=1m
$ diskutil eject /dev/diskN
LiveCD ISO to a bootable USB stick:
$ mount *\\ to see current drives
$ diskutil umountDisk /dev/diskN
$ sudo dd if=/path/to/downloaded.iso of=/dev/diskN bs=1m
$ diskutil eject /dev/diskN