I just found out that the emblem will stick in that particular slot
really well on it's own if you press it in far enough. To reinforce it I got 2 adhesives "Instant Krazy Glue" and "Loctite Extreme Repair" - this stuff holds up to 400 degrees without giving way
1) Remove the grille from the car, it will give you access to the rear of the emblem so you can seal the emblem to the grille.
2) I used the Krazy glue first to get a solid hold of "plastic-to-plastic" along the top of the emblem. This actually created a really nice hold but you can't always rely on one thing.
I let it sit for a good 10-15minutes...Krazy Glue dries pretty quick
3) I took the Extreme Repair goop and did the same exact thing and ran the paste along the edge. This stuff creates a flexible seal that should bond to both pieces of plastic. I also gooped up the clips that were close to the sides of some parts of the grille. I think there are 3 areas you can do this for more adhesion
You need to allow 24 hours for this stuff to cure but it starts to get sticky within 10 minutes.
I know it looks kind of messy but no one will see the rear part of the emblem anyway so if it holds, it holds.