How do you add Auxiliary cable to 2004 Grand Prix GTP 6 Disk no XM radio

How do you add an Auxiliary cable to OEM 6 Disk Monsoon radio (2004 Grand Prix GTP Comp-G) with out factory XM radio? I bought a PAC AAI-GM12 and hooked it up but it did not work. I looked into it more and it said it uses the harness for XM radio and you have to tune into the XM stations for it to work. It also said it will use an external CD player harness and use the Auxiliary option. I believe there is a code, or something you run through the OBD-II to make it XM compatible. If I make it XM compatible than I'm pretty confident it will work. Anyone been threw this before? Know the code, or if there is a code? How to make it work out? I'm already aware there is a lot of posts about people getting this to work, but the ones I found had XM radio.