Building a FreeNAS USB boot disk on OS X

1. Identify the disk using disk utility from the command line

   diskutil list

   
   Look for the disk that is your USB stick

2. Unmount the USB stick

   diskutil unmountDrive /dev/<your USB thumbdrive>

3. Transfer the image from your computer to your USB stick

   dd if=<path of USB Download> of=/dev/<your USB thumbdrive>

   This last step might take about 30 minutes