I had a look at this earlier today on a few different OS's.
The Mac is explicitly checked for in the flashall.sh script, so it aborts when you attempt to run it on a 'darwin' OS.
I then tried it on a Windows host, and sure enough, there's an extra tool that AlexT mentions that does not seem to be present, so no luck on Windows.
So it looks like the only option is to flash from a Linux host.