Ohh! You don't see an option to select the voice in the game, right?
You'll have to create a character and give it that voice ID. Open FFEdit, go to the Characters tab, copy El Diablo or somebody, name it something short-ish with no special characters, and don't use any spaces. Then give the new character your voice ID. I don't remember if you have to create a Template as well, but may as well do that just to be on the safe side. Click on the Template tab, find the same character you copied (just for simplicity sake), and copy and rename it to match exactly. Done.
Now that ID should show up in the character creator under whatever name you gave your character.
Sorry, I work almost entirely with built-in characters as a modder, so I don't think about that end of it very much.