1. Make the script
2. Export it
3. Import it with Import manager (Just like Custom models)
4.Find the GUI label: "AI". Like: "Unit", "Destructible", "Special effect" and "Hashtables". There, You find "Start campaign AI" and "Start Melee AI". Pick your taste. AND FINALLY, SET THE PATH OF THE TRIGGER TO YOUR AI SCRIPT.
Example:
-
AI - Start melee AI script for Player Variable: YourAIPathWillBeHere.ai