chronodev
CAGiversary!
Much like the Secret Key event for Rotom, the event is running over the Nintendo Wi-fi for only a limited time! There is no assurance this will happen again! My suggestion, find your local internet-friendly cafe and get your DS configured for it.
You will be able to get it via the Nintendo WFC August 3rd - September 13th, over a 1 month run.
See here for instructions!