CI_Session or EE2 Session class?

Using EE2, which is built on codeignitor. When I do this:

$this->EE =& get_instance();
$this->EE->load->library('session');

It only gives me access to the native session class inside the EE2 framework, how do I have EE2 load the CI_Session class instead? I’ve done some searching on this topic and haven’t found a solution that works for me without error.

Thank you.