How to Position a GuiText Prefab at Center of Screen

I want the game to display a prefab (GUIText: "GAME PAUSED") on the center of the screen whenever the game gets paused no matter what the resolution of the game window is. How do I go about doing that?

Below is the script I have written so far:

var bGamePaused : boolean;

var gamePausedPrefab : GameObject;
var gamePausedText : GameObject;

function Update()
            Time.timeScale = 0;

            gamePausedText = Instantiate(gamePausedPrefab, Vector3(Screen.width / 2, Screen.height / 2, camera.nearClipPlane), Quaternion.identity);
            Time.timeScale = 1;

        bGamePaused = !bGamePaused;

This script isn't displaying the prefab anywhere on the screen at the moment. I know that I also have to subtract half the width of my prefab from the x-position and the half the height of my prefab from the y-position, but that's currently the least of my worries as the prefab itself is not being displayed in front of the camera anyway. I know that the code works because the prefab shows up on the lower left corner of the screen when I instantiate the prefab at a position of (0, 0, 0).

GUIText and GUITexture objects use viewport space, which means X=1 is the right side and Y=1 is the top. So (.5, .5) is the middle.

Its easier if you just attach it to the script and just call it to show when you pause. Something like this:

var myTexture:Texture2D;
var myTextureWidth:float = 200;
var myTextureHeight:float = 100;
var isPaused = false;

function OnGUI(){

    if (isPaused)
       GUI.drawTexture(Rect( (Screen.width - myTextureWidth)*0.5,(Screen.height - myTextureHeight)*0.5, myTextureWidth, myTextureHeight), myTexture);