Hi,
I dont really have the schematics except the image in my previous post.
Voltage divider is simple I think, a pair of chinese Arduino Pro Minis, a power step-down too.
I will look if I have the sketches still, should be on my home PC.
About the optocoupler part, I had separate thread on that: (see the last post there, I had to invert the inputs)
http://forum.arduino.cc/index.php?topic=548866.0
Depending on your ESC, if that one has common ground for power in and power out, you can use just one arduino, but if they are not connected as it was in my case, you risk a fire and maybe damage to your LiIon/LiFePo battery, so opto between is a good idea.