How could I display text on the screen when I click on an item in my inventory?

I want to make books (I have the 3D Models) that when they’re clicked on (in my inventory) they’ll display text on the screen. I have no IDEA how to do it - but here’s the script

private var playersInv : Inventory;
private var item : Item;

@script AddComponentMenu ("Inventory/Items/Item Effect")
@script RequireComponent(Item)

//This is where we find the components we need
function Awake ()
{
	playersInv = FindObjectOfType(Inventory); //finding the players inv.
	if (playersInv == null)
	{
		Debug.LogWarning("No 'Inventory' found in game. The Item " + transform.name + " has been disabled for pickup (canGet = false).");
	}
	item = GetComponent(Item);
}

//This is called when the object should be used.
function UseEffect () 
{
	Debug.LogWarning("**<INSERT CUSTOM ACTION HERE>**"); //INSERT CUSTOM CODE HERE!
	
	//Play a sound
	playersInv.gameObject.SendMessage("PlayDropItemSound", SendMessageOptions.DontRequireReceiver);
	
	//This will delete the item on use or remove 1 from the stack (if stackable).
	if (deleteOnUse == true)
	{
		DeleteUsedItem();
	}
}

//This takes care of deletion
function DeleteUsedItem()
{
	if (item.stack == 1) //Remove item
	{
		playersInv.RemoveItem(this.gameObject.transform);
	}
	else //Remove from stack
	{
		item.stack -= 1;
	}
	Debug.Log(item.name + " has been deleted on use");
}

and the addon I’m using is here

If any of you smart people can come up with a script that will fit in between

function UseEffect ()
{
Debug.LogWarning(“”); //INSERT CUSTOM CODE HERE!

I would be so grateful.

if the book will be like a 2d texture in front of the camera i would use gui text http://docs.unity3d.com/Documentation/Components/class-GuiText.html
(the function should be in OnGUI() event

but if you want in on a texture, that’s what i’ve found as a solution
RenderTexture (Pro only) and then merge that RenderTexture into your Texture2D (with GetPixels and SetPixels).