CMers don't understand that they're accomplishing exactly zero in the positive direction and varying amounts in the negative direction. If they want to do so, they can do it without my help or support. In fact, Robert and I are probably not the only ones here who would gladly organize a 'pedestrian CM' to cork a bicycle CM, just to see what happens.
My answer to the original question would be, "Do absolutely nothing. CM claims their 'demonstrations' are entirely without leadership and are completely spontaneous. Therefore, just show up. To do otherwise would be to admit that the founding principles are based on lies. Which they are, but we'll try to ignore that aspect.