2002 Limited RDS Radio Aux Port Auxilary

I have a 2002 Buick Lesabre Limited with the RDS radio. How can I hook up an auxiliary input port? I know it comes through the cd changer cable. Is there one in my car if I do not have a cd changer? Where would that cable be located? If I do not have that cable, can I add it?

Other information:
I know some radios have the cd changer port on the back of the radio, mine does not, its a Class 2 Data Bus system, 1 connector in the back. I have had it out and looked.

Please let me know what you guys think, Thanks.