The relevant data for the events is all there in-game, the Mystery Gifts pretty much just flip the right stuff that lets you receive the key item, and the in-game script activates the event. pgt file, I select Manaphy Egg from the drop-down and check Enable Gift, this is what I get: Interestingly enough, this is what Pokésav generated, using the exact same.
For example (if anyone's interested) this is what PokéGen generates as an AR code that sets the Manaphy Egg.
