How do I get OnMouseOver to work again ?

It seems (from reading the forums) that Screen.LockCursor also disables OnMouseOver. Is there anyway around this problem? I want the cursor hidden during gameplay but I also ‘need’ the player to have the OnMouseOver ability as I have clues and game info scattered around the game area that work with popup GUI text/images.
This is the code I was trying to use-

#pragma strict
var crosshairTex : Texture; // Crosshair texture goes here
var position : Rect; // Position of the crosshair
static var OriginalOn = true;
function Start ()
     {
         Screen.lockCursor = true;
     }
function Update ()
     {
         position = Rect((Screen.width - crosshairTex.width)/2, (Screen.height - crosshairTex.height)/2, crosshairTex.width, crosshairTex.height);
         // Determines the width/height of our crosshair position
     }
    
function OnGUI ()
     {
         if (OriginalOn == true)
             {
                 GUI.DrawTexture(position, crosshairTex); // Draws the crosshair texture
                 Screen.showCursor = false; // Disables the cursor from being visable
             }
    
     }

Any Ideas ?

Cast a ray through the crosshair vector and test for a tag.