A lot of aftermarket rear panels come with a new bezel, this doesn't usually have the mount to fasten the vibrator too, so it maybe worth using the existing bezel on the new back.
I have managed to get the bezel off, the new bezel that came with my new back was cheap plastic and didn't have some of the screw holes or mounts.
Once I had the back and the bezel away from the rest of the phone, I used a hairdryer to heat up the glue which keeps it together, not overdoing it as the plastic will become brittle.
If you then squeeze gently the two sides of the bezel towards each other you will start to see some give in it.
I then put a spudger in between and slowly worked my way around, took around 15 minutes.
When it is off I cleared off the old glue and applied a very thin layer of new glue to attach securely to the new back.
Whilst it was off I also used a scotch brite pad to give the bezel the brushed aluminum effect. The whole thing now looks really nice.
The glue is very strong under the battery and you may end up snapping a few spudgers in the process so make sure you have a few spare for moving onto other steps. A screwdriver is to hard and will end up damaging the battery.