Copying ISO file to USB drive in OS X?
IMHO the easiest way is in terminal:


First run diskutil list
then insert your usb stick
and run diskutil list again to see the disk node (e.g. /dev/disk2).
Now run diskutil unmountDisk /dev/diskN
and do sudo dd if=/path-to.iso of=/dev/rdiskN bs=1m (or bs=1M with homebrew)
When finished diskutil eject /dev/diskN