[eluser]CodeIgniterNewbie[/eluser]
Doh! It's so simple and I missed it. Here's my solution:
// To set it
$fruits = array('apple', 'banana', 'orange');
$this->session->set_userdata('fruits', $fruits);
// To get it
$my_fruits = $this->session->userdata('fruits');
// To unset it
$this->session->unset_userdata('fruits');