Upgrading Stock Speakers w/ Stock Head Unit?

Hey guys,
I am doing a surprise front speaker upgrade for my uncle in his 2013 Toyota Tacoma Access for Christmas. I went through ********* for an upgrade package and i am all set to do this install. I just do not understand one little thing (which is embarrassing since i've been doing installs for 6+ years.

I know the wiring from the crossover to the speakers, that's easy. But, which stock speaker wires to i use for the input to the crossover? His tacoma has stock components, and i understand that the frequencies are split before the doors. I do not want to dig into the wiring too much right now, since a full upgrade to outboard amplifier is most likely going to happen in the near future. For now, can i connect the positive from both wires and the negative from both wires into the input on the crossover? Or am i just going to have to use one or the other? Any info would be much appreciated. This is my first time installing components on a stock system, so i want to cover my bases before i dig in.

Thanks,
Ben

 

the door speakers are in parallel. only crossover is a cap attached to the "tweeter". 6x9's run full range

either wire pair or both, it's the same

 

Hey
Have you done the speaker upgrade yet for your uncles truck?
I want to do the same thing on my 2014 AC with component speakers from Taco tunes, would like very much to know in better detail how you did the wiring input to the crossover.
Not sure if I understand the response you received on this, I have very little knowledge on car stero upgrades.
Also, where did you mount the crossovers?
I also plan to add rear speakers at a latter date and a amp.

Thanks so much.