Manual regarding stock stereo on 2006 Mitsubishi Eclipse?

I have a 2006 Mitsubishi Eclipse with the basic stock/OEM stereo. I'd like to add an option to connect my iPod as an AUX device, but I'm not sure the kit actually has an AUX option. There is one missing/paneled button on mine (an option I guess I didn't buy) opposite the eject button. Perhaps it was for AUX. I can't seem to find any information on what make/model the stereo is to even verify it might have such a connection option.

Can anyone point me in the right direction?