I found this nice event:
http://www.creationkit.com/AddInventoryEventFilter_-_ObjectReference
Something like:
Event AddInventoryEventFilter(CookingIngredientsList) Game.AdvanceSkill("Alchemy", 10.0)endEvent
Now, does CookingIngredientsList contain all alchemy ingredients as well or is there a better collection to use?
I plan on increasing the alchemy skill if ingredients are picked up, especially if gathered in the wild.
p.s. still at work, no way I can check creation kit or the game itself... this is all theory-crafting for now.