@Antares
Ok, I think I know how you could do it.
Create your quest and in the quest data tab select, from the event drop down list, script event.
Then go to the SM event node tab in the object window and double click the script event object.
Right click on Stacked Event Node:Script Event and select new branch node. A new stacked branch node will appear at the bottom of the list, right click on it and select new quest node.
On the stacked quest node that is created, tick the shares event box and right click on the stacked quest node and select add quests. This will bring up a list of quest forms, select your quest from this list and on your quest node add a condition to check if your quest is already running (GetQuestRunning [Yourquest] ==0).
Go back to your quest and create a new reference alias. In the quest aliases tab add your AI package to the alias package data tab and for the fill type select find matching reference from event and in the event data drop down select Ref1. To be safe also tick the optional checkbox in the alias tab.
Then attach a script to your activator that sends a story event to the story manager to start your quest.
Spoiler ScriptName MyActivatorScript extends ObjectReferenceKeyword Property QuestEventProperty AutoEvent OnActivate(ObjectReference akActionRef) QuestEventProperty.SendStoryEvent(akRef1 = akActionRef)EndEvent
The only problem is I don't know what the keyword should be! I think it should be a custom keyword that you attach to your activator but I honestly have no idea...