Old phone continuity tester
You basically want to make a line tracer.  You don't need a phone at the other end, just something that injects a signal.  This is what the old man did manually by whistling.  You can do it yourself by hooking a signal generator to one of the wires at one end, then probing around at the other end to find that wire.

One thing to keep in mind is that the signal will capacitively couple between wires in a bundle, more so the longer the cable is.  To get around this, use a low frequency, like 500 Hz, and have the receiver present a significant load, like 50 &Omega;.  The receiver can be as simple as a powered PC speaker with 50 &Omega; accross the input.  There will be a strong difference between the volume you get from the wire that has signal injected on it, and the others that don't.