Vertex color changing in-game?

Having trouble finding any answers about this… Is it possible to change vertex colors in-game? so, say, if you have a game with a paintbucket, instead of making a paint splat texture appear, is it possible to dynamically change the vertex’s color that the paint lands on?

Thanks!

I was facing the similar problem and looking for the solution. Thanks a lot as I got the solution. Now I can concentrate in further stages of my game project.