How to extend CI_Model?

[eluser]mjijackson[/eluser]
What is the cleanest way to create a custom Model class that extends CI_Model? I tried creating a custom MY_Model file and sticking that in the application/libraries directory, but CI does not instantiate it like it does for other libraries. So then, if I try and load the model library first:

Code:

$this->load->library('model');

I get an error saying that the CI_Model class cannot be found. Any ideas?