From: https://communities.intel.com/message/252147

This should work on OSX (not official instructions, just what worked for me):

• Install Homebrew by running the command:

  ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

• install dfu-util, coreutils, and gnu-getopt:

  brew install dfu-util coreutils gnu-getopt

• Download and extract Edison Image. http://http://downloadmirror.intel.com/24389/eng/edison-image-rel1-maint-rel1-ww42-14.zip and double click on the zip file to extract it. In your terminal change to the directory where you extracted the linux image (example your directory may be different)

  cd ~/Downloads/edison-image-ww36-14

• Run the flashall script and then plug usb cable into board:

  ./flashall.sh

Note: Flashing takes a couple of minutes and there is no realtime progress meter etc. When the flashing is complete you will see a message saying “U-boot & Kernel System Flash Success…”