Well, you could buy a ticket with the return segment < 330 days (since you need to have a reservation in order to issue a ticket), and then just change the ticket when availability opens up for the return that you want. But you may run into the problem that tickets are only valid for one year from the date they are issued. I don't think you can do 1/1/14-1/1/15 without doing two one-ways. You can shorten the trip by a day or two, but that still means you can't purchase your ticket until right before departure, which will likely be very expensive.