geometry needs to be transparent, and then the emitter needs to be higher in the parent-child list. So what you do is go to the nwmax panel named "Mesh Tools" (in nwmax 0.8b6 anyway. in yours it may be different). You'll see a button called "Order Children". Click that to bring up a widget which will show the children of the currently selected object. You may see that the order of children is different in this list than the order of children in the gmax "Select Objects" panel. What you want to do is move the emitter UP the list in relation to the model you want it to show through. So that means your emitter and the head node should be both attached to the same object.
as an alternative, you could make a TXI file for the texture which is transparent (if it is separate from the other textures). In that TXI, enter a line which says
blending additive
Results will be similar, but not exactly the same.
Hope that helps
Oh, you might also have issues with that particle showing through the neck or other nodes with transparency, in which case you might want do definitely do the TXI method, or look for different ways to structure the placement of that emitter.