After you downloaded the AI script, go to the default RO directory. This is usually located at C:/Program Files/Gravity/Ragnarok Online/AI. Copy and paste the downloaded AI in the USER_AI Folder. Make sure you empty all the files in C:/Program Files/Gravity/Ragnarok Online/AI/USER_AI before you transfer all the files. To activate your AI, type on your ragnarok console the command /hoai. Make sure that the Homunculus's behavior is controlled by User's AI. Use Rest and Call your Homunculus to load your script.
After installing, your good to go and your Homunculus will cast auto-skill without your intervention.