No problemo. If you have a red box or start stick that helps, though we use car batteries in serial too. Crank to max motoring on the external battery then flick the main battery on and give it fuel. If it hangs, shut her down and let it warm soak like everyone else says, then give it the beans again.
We never use an engine bay heater but usually throw a ceramic heater off a Honda 1000 in the cockpit. Sure sucks to have a frozen N1 or TOT gauge on start.