callbacks in library

[eluser]Unknown[/eluser]
Hey, codeIgniter community. I have some questions. Lets say I have controller:

Code:

class Test extends CI_Controller{

     public function test(){

           $this->form_validation->set_rules("test", "test", "callback_test");

     }

     public function test($str){

          doing stuff..... blah blah

     }

}

So, I using callback from same controller... How I can, put all my callbacks in library, so they can be reached from any controllers, or i can put same library in others projects? I hope will understand my question. Sorry for bad english.