Yeah, here is a technique you can try:
If you have your mask path, copy it. Add a new layer - cc glue gun, in the time line open the effect until you see "Brush Position." past the mask path after selecting Brush Position, and key frames should be added into the time line. Then parent your emitter to the brush position of the glue gun and then turn off the glue gun layer so you don't see it.
Hopefully that does what you need.
Best,
Derek Boettcher
Creative Management
BTH Media Group
http://bthmedia.com