I would fit a GROM unit.
This attaches to the CD socket on the back of the head unit (late Alpine type) and then offers connection to iPod, mp3 player, bluetooth phone, usb stick, depending on which model you choose.
I have the BT3 and play music from the phone and also have hands free call handling and control from the steering wheel.
Certainly, have a look at GROM before spending on a second hand CD changer.
(no affiliation, just a good bit of kit)