adventure basic language question

Hi, I am trying to have the sim play a continuous .wav file when my aircraft reaches a certain latitude and longitude. I know the conversion formula for the coordinates, but could somebody please show me an example of an abl code that would acomplish this. For reference what I am wanting to do is give sound to a rumbling volcano using one of the default thunder .wav files. Thanks for any help that you can give, JohnP.S. this is for FS2002