Changing a GUI texture while hovering over an object?

I have a cube, and I want the cursor (which is a GUI texture situated at the center of the screen) to change textures as it hovers over it. The GUI texture is not parented to the cube, because there are going to be multiple cubes.

http://unity3d.com/support/documentation/ScriptReference/MonoBehaviour.OnMouseOver.html http://unity3d.com/support/documentation/ScriptReference/Material-mainTexture.html

var male : Texture2D; 
var ren : Renderer;  //IS THE CUBE WHERE YOU WANT CHANGE THE TEXTURE 

    function OnGUI()
         {

 ren.renderer.material.mainTexture = male;

          }