We use Battles by GASLIGHT which is a supplement to the basic rule set ( the difference is Battles by is designed for larger forces)
The basic guidelines are units of ten men, with a commander in charge of up to three units, perhaps a steam vehicle or some form of mechanical item ( Impervious suit, automatons etc).Basic rule of thumb is three 10 figure infantry/cavalry units plus one mechanical item. IF you go steam mad and have too much technology on the table then the game will just become a slugfest between the vehicles.
The best thing to do is build a force around how you perceive your Russian army to appear in a VSF environment.Then look at rules afterwards( I know thats not how you would normally approach things in a standard wargame)
Before you decide to buy them come and have a game with is to see if you like it. We are not 100& happy with them anyway and looking at altenatives(And there arnet many specific VSF rules around) or are going to write our own.
If I was going to start a GASLIGHT VSF army from scratch I would first get enough infantry together say4 or 5 ten figure units, maybe inc some cavalry. 1 or 2 steam tanks and a special mech item like a walker an impervious suit or lightning gun. You will need a hero or two, who would be the corps commander or special characters.
Drop either myself a PM or Thundechicken or Jimbibbly or Dewbakuk or Bullshott and we can go from there.