There are a lot of venues from this show, and since they are big venues, I'm sure you will be able to get in ^.^
If you have the money to, I'd say to buy the CD and try the code with it! And if you know people who will buy the single but won't use their code, then ask for their code to increase your chances... ^^
If you know Japanese, it might be worth searching on twitter and other websites right away for people looking for someone to go to the show with/with an extra ticket (a friend cancelled on them, etc.) that they need to sell (sometimes these people have fanclub tickets)
Searching 椎名林檎 チケット 掲示板 will usually bring up message boards where people are trying to sell tickets, but try to do an in-person exchange, or pay-on-delivery so that you can make sure you get the ticket you paid for (there are also websites like ticketcamp.net which have been secure and easy in my experience) This can be hard if you don't know Japanese, though, because you have to deal directly with the seller... (Sorry, I don't know your level, so I'm saying this just in case ^^; )
If you end up having to get them through regular sales, be familiar with how to use the conbini machine (or have someone with you who knows what to do) and try to be there at about the time the tickets go on sale if you can, because they can sell out fast ^.^
Try to avoid buying tickets that people are trying to resell at a higher price if you buy second-hand.
Uhm, that's all of my advice I guess! I hope it made sense, and I hope that you get to go!!!!
