Bleach

On my car, I'm using different speaker locations, but the talking lady only speaks from the front left speaker. (actually, that's the CENTER speaker in the dash)

so I just left that speaker and the original wiring alone. I have re-done all my speaker wiring and put in a CD player, so I know that the talking lady's wires don't go near the factory stereo. I would say to find the two wires for the center speaker and run them through a separate 20watt amp or something and then back to that speaker location. Buy a decent 4 inch speaker for it, or you can run it to a separate tweeter. A tweeter would probably sound fine for her warnings, and you'll be able to hear the high pitch sounds better over road noise and other music in the car.

If she doesn't talk even with the factory speakers hooked up to that center speaker, then you have other problems with the system....