Splicing into door speakers at factory amp

[shlimm]

Im trying to find a way to wire in a speaker box without having to run wires from my trunk all the way to inside my doors. I see on the HK amp wiring diagram that there are wires running to there for the door speakers. I was wondering if those could be used to deliver sound to the speakers.
I already tapped into the subwoofer wires to install an aftermarket sub