I'd follow adidasoriginals and adidasca on twitter, they'll tweet when it goes live. You go on that page and it'll turn into a queue kind of like Nike's.
There's an inventory link that will also go live to show you how many pairs, its posted somewhere in this thread. There's also the old backdoor link that'll directly add to your cart, skipping the queue. I've had a feeling that this method won't work anymore judging from the way it's added to the cart now.
I haven't tested it yet for 350 but I whipped something up that'll generate a cart url based on the productid and your size code. If this does work i'll figure out a way to get it out there.