Create your Waypoint in Mapsource.
Place your waypoint in the middle of a road.
There is a box in waypoint Properties that has a proximity Value, write your value in there. eg 0.4 km = 400 meters.
Now save the file as a gpx file. eg noise.gpx
Place the file in a folder eg c:\mypoi\noise.gpx
If you want to add an Icon then place it in the same folder as c:\mypoi\noise.bmp must be the same filename
(You can download garmin Icons from Various sites on Internet)
Now run Poi Loader in automatic mode and point it to that folder.
Once Poiloader loads your POI into the gps you need to navigate to the point and it should beep when you get to 200 meters away.
Make sure that proximity alerts are switched on in the GPS.