Third (or is it fourth?) brake light help, please

I just installed the OEM spoiler to my '03 LX sedan, the one that comes with the built-in brake light. I ran the wire into my trunk, and it looks like I have a couple of options:

1) Run it to the existing interior third brake light (the one between the two rear speakers). However, I'm having a b**** of a time getting that brake light out and there is no exposed wiring for me to splice into.

2) Run it to one of the rear brake lights (specifically, the driver's side). Behind the trunk foam there is a bunch of wires of differing colors that lead to the light. Can anyone tell me which wire is for the brake light, and what is the best way of going about doing this?

Many thanks in advance.

i know in my '99 there are seperate wiring harnesses for each bulb. just pull all of them out, except the turn signal and back up, and see which one lights up when the brakes are pushed then tap into that one's wiring. if you want to disconnect the 3rd brake light in the rear window, you'll have to remove your rear dash. there are 5 fasteners that are on the front when you put the seat down that have to be removed. the pull the rear dash forward and up. then you can reach under and unplug the light, or take it out by pushing on the plastic retaining clips

Thanks, got wake?.

In my '03, I believe all the wires lead to the same harness. I had no idea you need to take off the whole rear shelf to get to the light. I'll try that, thanks.