When the beta registration re-opens, you'll go to the SE website and apply for it. I'm assuming that with it being Open Beta, we'll all get a code. You'll get it via email. You'll supply the patcher with the code you got via email, then it should work.
At least that's how I've come to understand how it's gonna work.
FFXIV: Raxion Gunsoul - Brynhildr - 50PLD 50SMN 50SCH 50DRG
WoW: Raxion - Greymane- 90 Druid
FFXI: Nion - Asura - 99 BLU, PUP, SMN, DRG, PLD 50+ DNC, NIN, MNK, THF, WHM, SAM, WAR