Hard to say and execute. Don-Kuban to me is going to rebel sooner or later. The North was more of Entente fearful of what is happening in Russia and finding anyone with half-credibility to lead a smattering of locals to oppose the Bolsheviks. Central Asia... woof, that'd be hard, because you have a variety of factors, including (in some parts) oil, religion (Islam vs. declared militant atheism), Soviet neo-imperialism ("we want a brotherhood of all peoples, comrades... dominated by Russians). As Sukhov says in "White Sun of the Desert" - "The East... is a delicate thing." As for Siberia, any little thing could have tipped it over the edge. I am not sure if any little thing would have helped make it less blood soaked. Probably a combination of factors. But the chief reason for the blood is the mule stubborn Soviet approach to changing Russia that made them enemies everywhere. But asking Bolshevik to be less Bolshevik is a bit ASB at this point of the juncture.
One initial bloody approach that could save some blood later, at the initial October Revolution, there were a lot of Tsarist officers rounded up or already rounded up and taken prisoner. Some key officers escaped due to the confusion and lack of planning by the Bolshies. Had the Bolsheviks executed their Tsarist officer prisoners via "laws of military time" (an un-lovely euphemism), they could have shortened the war, in my view.