2003 CTS w/o Bose

My friend wants me to install four speakers, and a JL cleansweep in his CTS. He says the car has the non-Bose premium sound with a factory amp. His idea is to install four speakers and the clean sweep into the factory radio and amp system. I'm about 99% sure this won't work (as far as installing in the JL), but he isn't convinced.

Im a correct? The factory radio doesn't have RCA outputs and the factory amp doesnt have RCA inputs, Correct? Also, if we figured out a way to use LOC's would that lessen the benefits of the JL's auto-eq and calibration?
I told him it would work if we were also installing amplifiers as well.

He bought it online and the salesperson said it would work with his system.

Thanks for the help and advise.