Purchasing another registration code and two-boxing?

Hello, all. From what I understand, it's possible to two-box characters off the same account as long as I have two registration codes. I know SE said in their FAQ regarding multi-boxing that when the service center (Mog Station, I'm assuming?) went live there would be a way to purchase registration codes, but I'm not seeing anything like that. Have they implemented a way to purchase extra registration codes without buying extra full copies of the game yet?

And to anyone who currently two-boxes off the same account (if it's even possible yet), what was the process you used to achieve that, as far as purchasing and registering codes to your account?

Thanks!

I believe it has to be separate accounts. There was a dev response a few weeks ago that was quite enlightening on this subject tho.