In the game box, TAKE OUT the insert/instructions. On the back of the insert is a registration code (4 groups of 4 letters/number). This is NOT the Square Enix Members serial code that is on a different piece of paper in the case. If you have a digital copy, I think the code is in an email. There have been other threads about looking in your junk folder for the email with the code.

In your PS3 main menu/XMB go to PlayStation Network, Account Management, Redeem Codes, and enter the registration code. It will try to start downloading the game client. If you already have the client installed, press Cancel.

Restart FFXIV and go through the process of connecting you service account. Make sure you connect to the account your characters are on. If you choose Create New Service Account, you will NOT be able to access the characters you've created. The names of both of my characters AND the beta accounts were listed on the screen where I choose.

After that I was able to get back into my account. Not into the game though. The servers are full.