I managed to get the flashing process for the beaglev-ahead board working on my mac and thought I would put up a note here as the docs are missing.
Firstly I used brew to install the andoid tools.
brew install --cask android-platform-tools
Next I navigated to the deploy directory after extracting the downloaded image file and edited the fastboot_emmc.sh file, removing the section at the start which requires root.
# if ! id | grep -q root; then
# echo "./fastboot_emmc.sh must be run as root:"
# echo "sudo ./fastboot_emmc.sh"
# exit
# fi
Then I simply ran this script and it imaged, then booted the board.
Then I installed the tio command which is a pretty neat serial console tool, plugged in a serial to USB converter board to the port on the beaglev-ahead board, located the serial port and connected.
brew install tio
ls -l /dev/tty.*
tio /dev/tty.usbserial-A10442LA
Hopefully these notes help others, now working on getting a yocto build environment up so I can customize the image. 
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Happy hacking.