I sent him a PM, but I'll try to explain here as well. First you need to purchase the AOEM-NIS2 from Pac Audio. I ordered mine directly from the company but I believe they make you go through a distributor now. This unit ties in between the factory head unit, and the external Bose amplifier. Once installed, it takes the signal going to the Bose amp and creates front and rear low-level RCA outputs. YOU STILL RETAIN THE FACTORY BOSE SOUND THROUGH THE BOSE AMP BECAUSE IT DOES NOT CUT OFF THE SIGNAL. The unit also comes with a remote turno-on wire, but for some reason it didn't work in mine. (I had previously installed this unit in my 2003 Nissan Murano W/ Bose) I just found the turn-on lead for the Bose subwoofer amp under the driver seat and tapped it there. (It's green/white for future references.)
Sound quality is great and the bass is great as well.