Is it possible to use a function like the .ini function AddActorSpawn during a scripted game to start some form of skirmish in the middle of a mission, or will I need to manually compute it in the script?

The wiki, as per usual, turned out a nil.

This problem has been kinda-sorted. Please read the following posts.

Well, Maginot starts spawning Dummies after a (very)short amount of time, I assume you could look at those scripts to figure out how to spawn units like that, and then just have something at a certain point in your mission activate the script.

If I recall correctly, Maginot had a couple of modes, all of which had the same spawns.

Mode 1 = Wait
Mode 2 = Spawn left
Mode 3 = Spawn Both
Mode 4 = GTFO

So I'm not sure it's the best example of mid-mission spawn changes, more like a well-designed pause screen.

Ah, I forgot about Maginot. You're probably right, alpha.

It looks like it's all manual, not like I want at all. Ah, well. I'll see what I can do.