trying to figure out how to achieve a flowing paint effect.

What I'm working on is creating animated brush strokes as particles that follow a path. This video is basically the effect I'm going for:

My goal is to create an animatable path for the particles to both spawn on and flow around directionally. I've been working with a combination of layer emitters and motion paths inside trapcode particular, but it's still not working very well. If anyone has any tips or another way to approach this I'd be excited to hear it. I'm using after effects cs6.