Can I exclude a civilization from random selection?

[risikawi]

I haven't played for a while, so I don't remember much about moding. So here's a thing - I usualy just select "play now" to let game choose a leader for me to play, but I don't want to play Russia, which it keeps on selecting lately. I remember reading somewhere it is possible to make a simple mod to make a civilization unpleyable, while leaving it in the game, but now I can't find anything about how to do it?