I recently created a fireball using pyro, I want to render it out, and apply a vector blur in Nuke instead of rendering with motion blur. I have looked at some other methods online of exporting the vel pass. However, they all involve using a shader and I already have a pyro shader assigned to it. I'm inexperienced in using vex variables as well, so does anyone have any solutions for this?

Check attached project and I marked custom or edited nodes by RED color 8)

Thanks Joker386! I was having this trouble as well, and your scene really helped me get a velocity pass out!! cheers