The reason I suggest that is that when someone else drives the car a buzzer
would drive em bloody crazy.

PS if you want to do what ya suggest, then within the wiring loom going up
to the steering wheel theres two cables within there that you can use. From
memory ther are green small wires with a trace on em. If you want to connect
one device to both left and righ blinkers then you will have in install two
Diodes to prevent backfeed. Doing this will allow a buzzer to beep on and
off with the lamps if thats what you wanted.

If this is something that you can do all you need is a soldering iron and
two diodes plus your buzzer. Shouldnt take you much more than an hour once
your parked up. ;o) If you dont know how to hook that lot up repost and
either me or someone will guide you through the process.