No, it's impossible. You'll have to grab the Celebi event, then get the Ticket. I found this out the hard way. After a bunch of trouble, I was able to regain the Ticket so when I finish my game for TMs and stuff, I'll just split the game up in SRs and breeding/Eon Ticketing. :PI just sniped an Eon Ticket on OR. I downloaded the Celebi event a few days ago.
Is it possible to rearrange the two rewards to get Eon ticket before the Celebi? StreetPass Eon Ticket doesn't show in my Card Album so I can't just shuffle it around.
Naturally, this is only possible because of Powersaves.
If you have a different game, you can also use that to get Celebi. I have the event on both X and AS right now.