I ride my CE 04 throughout the year but if I were to lay it up over winter I would charge the propulsion battery to around 60%; plug a CAN-BUS compatible 12V battery charger into the DIN socket; put some insulating layers under both tyres and perhaps apply some corrosion protection to the brake caliper bolts (since mine are orange after three unprotected winters). Also, I would occasionally rotate the tyres so that they don't spend the whole winter in one position. If you have a centre stand I would use that rather than the side stand.
I keep mine in my basement garage the temperature goes about 12 cel, 60 to 80% battery center stand and I lift the front so the wheel don't touch the ground.
I also tell him everyday that spring will come soon...
Yves