Handles.RotationHandle  

static function RotationHandle (rotation : Quaternion, position : Vector3) : Quaternion

Parameters

Returns

Quaternion - the modified rotation Note: Use HandleUtility.GetHandleSize where you might want to have constant screen-sized handles.

Description

Make a Scene view rotation handle.

This will behave like the built-in rotation tool in Unity. If you have assigned something to Undo.SetSnapshotInfo, it will work fully with Undo.

Rotate the attached object from the Rotation Handle.

//Create a rotation handle at (0,0,0) and rotate any object that has "RotateAtPoint.js"
// attached from 0,0,0.

@CustomEditor (RotateAtPoint)
class RotationHandleJS extends Editor {
    function OnSceneGUI () {
        target.rot = Handles.RotationHandle (target.rot, Vector3.zero);
        if (GUI.changed)
            EditorUtility.SetDirty (target);
    }
}    

And the script attached to this handle:

// RotateAtPoint.js
// This Script has to be outside of the editor folder.
//
// Usage: Just Place this script on the object you want to work the handle with.
// And control the Object's rotation from the handle that appears at 0,0,0 when 
// This object is selected.

@script ExecuteInEditMode()
var rot : Quaternion = Quaternion.identity;

function Update () {
    transform.rotation = rot;
}