There is no built-in function or a method of a List that would allow user to add a new element in a certain position of a List. I've wrote a function that does this but I'm not sure that its a good idea to do it this way, even though it works perfectly well:

```
def insert(list: List[Any], i: Int, value: Any) = {
  list.take(i) ++ List(value) ++ list.drop(i)
}

```

Usage: 

```
scala> insert(List(1,2,3,5), 3, 4)
res62: List[Any] = List(1, 2, 3, 4, 5)

```