I don't know if there are any vehicle specific items, but they do sell a line level converter that will convert into an RCA output. actually, I've got one you can just have if you want to pick it up. took it out of a BMW I had about 4 years ago
quite simple. line level converter and the wires will be in the rear decklid in the trunk. still need power wire ran to front. ground can be underneath rear seat. i believe i used the bose amp for the remote wire. But it's been probably 7 years since i did that install.
The Bonne might be different than the GTP, but I grounded my amp under my back seat, ran the power wire to the battery which also under the back seat, and then tapped into the IGN3 fuse in the fuse block, also under the back seat (lol), for the turn on lead. Amp operates in ACC and ON only.
Line out converter like everyone said. You can make almost all the connections under the rear package tray right by the bose amp. The one bad thing about the factory head unit is the base roll off, at higher volumes the head unit cut base to save the factory speakers. You will have to run power from the battery, clean ground to the cars body, to start with. Then the use the pink wire, B11, at the bose amp for your remote turn on. Connect the line out converter to the yellow and brown wires, A8 and A7, for signal. That should be full range signal going to the left rear speaker. Also, the 6x9 speakers in the rear act as a pair of pathetic subwoofers lol.