Aux Input for a 07 Malibu

Hello,
I have an 07 Malibu with the 6 Disc-cd radio & was wondering if an auxilary input can be hooked up to the radio to connect an ipod/mp3 player. The radio has a Source button & wasn't sure if there was a wiring harness available from the factory or if using an FM modulator is best.

Thanks!