You can't flash this yet (I'm working on that, I promise) but you can boot from it!
NOTE: THIS IS A WIP. Not a lot has been really tested yet and this is posted merely for your enjoyment atm.
I don't suggest flashing anything yet, not that there is anything to flash heh.
Also, I take no responsibility if you break your watch, yada, yada.
To do this, make sure you have Android's tools (for fastboot), an unlocked bootloader, and the watch connected to your computer in Debug mode.
> adb reboot bootloader
<wait for the reboot to happen>
> fastboot boot /path/to/recovery.img