It looks like there's three bolts and a couple of clips that secure the whole license plate/handle section to the door. Maybe the whole deal needs to come off to reveal how to get the chrome bit off.
If someone has access to the GM EPC maybe they could post the exploded diagram of this part. Unfortunately my copy doesn't run on Windows 7 and I don't have an XP machine to install it on.
Let me know if you figure this out...I may try to pull mine off this weekend if it doesn't rain.
