Once i had the speaker wires isolated, i just connected a 9v battery to each pair until i heard a pop, then i just figured out where it was coming from. You can also get a multimeter to test for polarity. If you want to test for ground, just hook up one lead to closest metal and then to each of the wires until you get continuity. I dont think this is how most do it (i just have the multimeter because i do electronics.)
-ivan c.
