Anarchists are a chaotic lot. While an anarchist will tell you that anarchy is not chaos, the fact remains that anarchists, if you interact with them, tend to be very impetuous and passionate. Like Marxists, but less dogmatic and with spines.
This presents an opportunity. We need to find those subgroups of the anarchist movement that are closest to us (national anarchists and ancaps) and begin bringing them closer. This will exert a pull on the rest of the movement. Additionally, we need to begin agitating for a genuinely revolutionary anarchism – one which sees radicalization as the only route to a victory. Recalling my mantra that we must radicalize the Left as swiftly as we can in order to create a backlash, we see that this has the dual virtue of causing the salvageable anarchists to come to us (dragging some useful idiots with them) while agitating the unsalvageable ones into jumping the gun and becoming loud enough to cause tension with the Marxists.
On that note, recall that the alliance between red and black has always been uneasy, and cannot survive. The closer they stick together, the more the increasing rate of radicalization (which we must pursue) will pass from our false anarchist memes into the Marxist movement. Note that, as they radicalize, their differences will become apparent, causing them to violently reject one another. It will be interesting to see how this plays out.