(im new) another amp/sub install question

Hi all. I have a 2016 CX5 GT W/BOSE. I have already put some Infinity Reference 3022's in the front (awesome upgrade), and some kicker DSC670 6 3/4 in the rear doors (louder and clear but no bass) all running off stock amp. I just purchased a Rockford R500X1D and a Kicker Comp R 12" box. I have been researching but I'm not expert. I've done some installs in the past but with aftermarket Head Units. I also bought a Scosche LOC90 to install the amp. I would like to tap into the wires at the amp location under the drivers seat and put the LOC there so I don't have to pull the head unit. I have looked at the wiring diagrams but don't really understand them and wanna be sure. What color wires do I hook the LOC up to at the amp location?? Its a mono amp and the 12" Kicker is one 2 ohm coil btw. I'm also not sure about taping in before or after the amp. Sorry for the redundancy but I just couldn't find the exact info. Thanks for your time.