Thank you for the first answer this gave me alot, but not the complete answer. After fooling around with your answer i figured out i had to do the following:

public var prefab:Transform

function Start() {
    Instantiate(prefab,new Vector3(0,0,0),transform.rotation);
}

And link the prefab i want to create to the prefab var in the script.

nearly the same as the first answer, although i got alot of errors because i was using exacly what the answer stated.

Instantiate(transform,position,rotation)

where transform is the prefab.

For instance:

var player : Transform;

Function Start() { Instantiate(player,new Vector3(0,0,0),transform.rotation) }