Answer by Jessy

You just need a reference to the instance script1.

http://unity3d.com/support/documentation/ScriptReference/index.Accessing_Other_Game_Objects.html

For example:

private var x;

public function SetX (x) {
    this.x = x;
}

.

class Class1 extends UnityEngine.Object {
    function DoSomething () {
        (FindObjectOfType(Script1) as Script1).SetX(1);
    }
}