Got it working with Windows 7
This is how I done it.
(Ensure you have ADB installed - If not google "ADB setup 1.3 windows")
Download the chosen firmware and rename it to update.zip
Download roligov's command file
remove the .txt extension that windows gives it when you download it. The filename should just be "command" with no extension otherwise you will get the failed message when you reboot to recovery.
Now run command prompt as Administrator
(I will use C:\ as the file location example)
adb connect "Fire TV IP Address"
chmod 777 cache
chmod 777 recovery
ctrl + c
adb push C:\command /cache/recovery
adb push C:\update.zip /cache
--- Go make coffee or take a ****....The pushing of 466MB takes forever.--- (Took 2 minutes over LAN for me)
adb reboot recovery
Many thanks to roligov for the initial find to set me on my way.