It's under the mental ray textures in Hypershade, mmd and drop it over the material. Again make sure that fg is turned on in render settings and also adjust the fg contribution on the node itself.

Keep in mind that this is light emitting geo and not glow though so try out all these things and see which works best with what you're doing. As gen said it's hit and miss with glow in maya and you only get one node for shader glow so you have no real control.