You can't get the Eon Ticket anymore for Emerald. It was only handed out by special promotion, so people could get it by going to some event or buying a particular issue of Nintendo Power. Even for those people who got it, the only way to share the limited amount of tickets is by mixing records, which requires local people who have the game, and a GBA, and the link cables.
So when it comes time to pick which legendary roams Hoenn, pick carefully which one you want to catch. As for the other Lati, you're out of luck.