If you want to make sure your halos won't fall off again, you need to drill some tiny holes and secure it with wire. I didn't trust the adhesive and someone on here used--I think--.020 safety wire to hold them in place. I found some silver coated copper wire used for jewelry making when my daughters were at Michaels and I used that to make sure my halos don't fall off in case the adhesive fails.
Are you going to use the Morimoto Mini H1 projectors? There is a pretty nice write-up on hidplanet.com on retrofitting the Charger headlights. IIRC, the guy had to modify the housings a bit because the space a bit shallow for the projector. Anyway, good luck with your retrofit. It makes sense to do since you're going to have to open your headlights anyway.