Mustang Mach 460 amp bypass?????

[ddb]

I have a '94 Mustang GT convertible with the Mach 460 sound system. I just want to tap into the speaker wires and add a couple of Rockford amps and throw away the factory amps. My local car audio store told me the only way to do this is to run some speaker wires directly from the speakers. I don't feel like tearing my car apart to get to the speakers. I tried the Metra amp bypass harness solution but I am getting power from one of the wires that should be a speaker wire. You wouldn't know which wires are the speaker wires or where on the net I could download a wiring diagram for the Mach 460 system? I have 2 factory amps in the trunk on this system.