This is where the guide gets a little less concrete, but hopefully, it will make sense. Unlike hats and miscs, these Killstreak Particles aren't made with bones and control points relative to where they should be placed. I've found that the best method is to pose your model first, make any facial adjustments, THEN add the effects. However, we sometimes find a better pose after the fact.
I'm not an expert with bones or control points, so this section doesn't have to be followed very closely. It's just more my recommendation. There are several controlPoint bones to each effect, but their positioning doesn't seem to affect anything, apart from controlPoint0.
When you import the effect, lock your model's rootTransform bone to the Particle's transform bone, select the transform bone and drag the zero slider to full. Secondly, lock the model's bip_head bone to the Particle's controlPoint0 bone, select the controlPoint0 bone, and drag that zero slider to full as well. With the controlPoint0 bone still selected, position it in the view port near the eye and ♥♥♥♥♥ the playhead to get an idea of how the effect looks. Adjust the position as necessary.
If you let the scene play a bit and watch the particle system, you will notice it juts out a bit (presumably to compensate for the forehead or hat). You can actually control the direction it juts out in with the Rotation manipulator.
As I mentioned, this section isn't concrete, but as for right now, I do know it works. I will update this if I discover simpler or more effective ways of doing this.