I remember reading about usage of different paints about 5-6 years ago. I think it was over on AVSForum. I never did any experimentation with paints. You might not have the amount of gain that a specific screen material would have (I don't know). Also, you would have to make sure you used a perfectly flat surface. Many residential houses nowadays have textured walls.
One thing to keep in mind is that you really need to have a border or some way to black out the entire area surrounding the screen. There is much light that would reflect off the front wall, event though the projector is primarily aimed at the screen.