With the CE digital upgrade, there isn't a code involved. You buy it from the MogStation and it's applied to your account. All you have to do then is pick up the in-game mail with your items. (This is the only way to take an existing standard account and add the Collector's Edition items to it without adding a new platform as well.)

If you bought a CE version of the game, that's only good when either setting up a new account or adding a new platform (PS3 if you'd only had PC before, or PC if you'd only had PS3 before) to an existing account.

If you've been on PC before, and are adding a PS3 code (whether CE or not), you need the code on the back of the little booklet in the game box (the one that's in Sony's XXXX-XXXX-XXXX format). Enter that code in the Playstation Network. The first time you start the game from the PS3 it will have you log in and either associate that copy with your existing account or create a new account for it. Obviously, if you want to use it with your existing characters, choose your existing account to associate it with.

If you've been on PS3 before, and are adding a PC code, log into the MogStation, select "Account Services" and then "Add Windows Service." You can enter your code there.