said by tp0d:i will explore the option of the anti-freeze you described however the pump is built into the boiler so i am not sure a bigger one can go in unless an external one is added . As far as the genny several threads indicate an outlet can be wired to the boiler power supply and the boiler put on a plug so it could be plugged into a small genny. The genny would need to be delivered (a small one). Due to the pump size may need increasing the genny may be the easier option on the two. The genny could be stored right in the corner of the boiler room when not being used as well.
Best way to completely combat that, would be to refill the system with a 40% solution of propylene glycol, which would not freeze until -8F. You may have to upsize the pump, as glycol takes more head pressure to pump.. Glycol has a 10-20 year life, so you wouldnt have to worry bout changing it often.
You can run the boiler off a generator, no problem. Even if it isnt close, a 100ft extension cord would probably work. The boiler only draws a max of 5-6amps