Pretty old thread, but I can still hope that someone sees this, right?
Gamefreak posted exactly what I was looking for... but I'm using a Codebreaker. It took a few hours, but I was able to scrounge up the Codebreaker versions of the event codes.
Master code (This is the one I used. There seem to be a few floating around.)
00006FA7000A
1006F5CC0007
Birth Island
820322E43A1A
Puts you right in front of the ferry on the island. The puzzle's just a few feet in front of you.
Navel Rock
820322E4421A
Again, it pops you right in front of the ferry on the island. Lugia's on the bottom floor, Ho-oh's on the top.
Faraway Island
820322E4381A
This one actualy puts you on the other side of the map, away from the ferry. Save and reset the game when you get here, then step through the opening in the trees behind you and Mew pops out to play.
Figured I'd save anyone who's looking a lot of trouble.
Wow, I haven't been on here in forever. The last I saw we were trying to start playing as Data Roxas (with little success), and now there's "Play as Marluxia" (another horrible problem) and "Play as Luxord". Which brings to mind a very important question:
For these codes, whether it be Luxord or Sephiroth, do you still have to be in the fight against that character, or was free roam figured out?
The way the story plays out, it's easier to understand If you play it TVA. There are a lot of things that don't make sense in Terra's story until you finish Ven's, for example, but you'll understand less if you play Ven's first... just do it. :)