Technically yes you can but the sound quality will suck. If you want to do it right you have to get an amplifier and a wiring kit. Get it installed professionally with some sound insulation for the best results.
i have a toyota highlander but i couldn't hook it up to the cd player so what you can do is hotwire the back speaker to the amp... so instead of the wire going in to the back of the cd player it will just be connected to the back speaker.