After reading this article Browser Warning
I decided to try my hand at it.
The Whisper 2000 unit is very old and hard to find. But any WalGreens has the ListenUP personal sound amplifier for $14.95. Score!
You'll also need some speaker wire and a clamp of sorts.
First open the Listenup by prying off the side panels and undoing the four screws.
Next pull out the microphone and cut the wires. Remeber which wire is hot and gound.
Next soilder your speaker wire to the microphone and then to the wires inside the listenup. You'll want to loop the speaker wire though the housing of the case so if you drop it the speaker wire doesn't get pulled out.
Bolt the case back up and use some shrink wrap to cover those wires.
Now with the mic use some hot glue to glue it to the end of the clamp. Use electrical tape to hold it all together, once again loop the speaker wire so the mic doesn't get damaged.
If yours doesn't look like this you did something wrong.
To use simple place it on the block where a knock sensor would go and go out and drive.