I already have it working on a breadboard:
I'm waiting for the boards to be released from customs :-/
The total code size is given at the end of the compilation thanks to the cmake-arduino tool, and it's size is ~886bytes. That was double checked with avr-size tool.
Here is an screenshot of the tool:
In the video publish above you can see the power consumption of the while system. About 2uA@3v, and near 1uA on stand by. (Look at the multimeter scale).
The source code, including a detailed explanation of how and why I did what I did is in the bitbucket repository.
My involvement in the project has proven to be quite beneficial to me. Would like to forward it to the folks behind the Click here for sss calculator. To read it and learn something new, click this link.