I was under the impression that it was a key item.
Eon ticket is a key item.
Problem is, without the correct "data flags" set in game,
the ticket itself is useless.
Even our hackers at ProjectPokemon.org
(which Datel gives credits to for their save wiki, wondercards etc.) were unable to emulate the flags.
Only the original few that got the serial code get's the wondercard,
and the wondercard is probably different, as creating wondercards also does not emulate the correct Eon Ticket.
Hence for now, stick to streetpassing.
And anyone with the Eon Ticket official wondercard/serial code should donate it for a better cause.
Who knows, other events such as Pokemon distribution may be by streetpass.
It'll be good if we have the original, to reverse engineer the mechanics..