Mount the Snow Leopard DMG by double-clicking it. Note the mounted volume name (e.g., Mac OS X Install DVD).
Open Terminal and type:
diskutil list
Find your USB’s identifier (e.g., /dev/disk2). Mac Os X 10-6 Snow Leopard Download Dmg
Unmount the USB (but don’t eject):
diskutil unmountDisk /dev/disk2
Restore the DMG to the USB:
sudo asr restore -source /Volumes/Mac\ OS\ X\ Install\ DVD/InstallESD.dmg -target /dev/disk2 -erase -format HFS+
This takes 15–20 minutes.
Once done, restart your Mac holding the Option (⌥) key, select the USB, and install Snow Leopard. Mount the Snow Leopard DMG by double-clicking it
The dd command failed. Erase the USB drive in Disk Utility as "Mac OS Extended (Journaled)" with a Master Boot Record (MBR), not GUID. Then try the dd command again.
Tagline: No new features. Just a better Mac. Open Terminal and type: diskutil list