Well....
If you attend these events on your own, you can get a Wonder Card. Wonder Cards allow you to "share the love," or more so, the event Pokemon by distributing the event yourself to friends, relatives, etc. These Wonder Cards can usually only be used so many times before the thing doesn't let you share anymore.
Anyways, let's get to the point: The Darkrai event was confirmed to use local Wireless, so I assume that means Wonder Cards. I've tried a JPN PBR Wonder Card from my JPN Pearl to US Diamond. My Diamond WAS ABLE to pick up the signal, and receive a JPN PBR Pikachu.
So....
Give it a shot, maybe you can succeed. If all else fails though, you could Wonder Card with the other attendees, or with whomever you tagged along with.
Also, the region of the DS is irrelevant, all of them are technically the same (except the iQue DS [Chinese DS]).