Messages

Yes. Just start a game with the storyteller you want. Save it. Look for the "Storyteller" XML block. Copy it over the one from the savegame you want to modify.

will you ever add the way to change a ai director  mid-game in the menu?

Probably yes.

If I may, I think this is a bad idea.

In the future the AI Storyteller may need backward story references. Now the AI Storytellers are basics but (I hope) they will evolve using real AI features. And changing the Storyteller in the middle of a game would corrupt a whole game experience.