how to load images from hard disk to gui buttons?

hi. i've been digging this out for about 1 week but i haven't get a result: how to load some images from some folder in player's hard drive to gui buttons automatically? consider that the folder and the images' names are predefined. i just want to load images to buttons so that user can use them as a material to an object in game. is there any way except using "for" to create the buttons automatically in OnGUI function? cuase it wont let the built game run! giving "crash" error... help me plz.

Assuming this is a stand-alone game you can use the WWW object with file:// prepended to the path to load a texture. Do it in a Start routine, not OnGUI

var myGUItexture : Texture;

function Start()
{
  www : WWW = new WWW ("file://path/filename.jpg");
  yield www;
  myGUItexture = www.texture;
}

function OnGUI()
{
  if (GUI.Button (Rect (10,10,50,20), myGUItexture))
   do something
}