This event can only be triggered with the CPH.TriggerCodeEvent C# Method. You can use two methods. With the first method you can use the variables of the current action. With the second method you can specify a dictionary of variables for the trigger.
When registering a trigger your trigger will end up in the Custom folder under triggers. You can nest the trigger in multiple folders by using the catergories parameter. To give the trigger a name use the triggerName parameter. Use the eventName parameter for a name only used in C# for triggering the method.
Variables are dependent on the custom event.
public bool RegisterCustomTrigger(string triggerName, string eventName, String[] categories)
public void TriggerCodeEvent(string eventName, bool useArgs = true)