I played around with a small magnet and tested the location on a "REAL" dock station, and found that the magnet sensor is actually behind the battery door. If you have a big magnet it will trigger it from farther away, so the smaller ones are better to find the location. If you open the door you will see a silver clip like thing (2 rivets and a sponge on top to hold the battery), that is where the sensor is, better reading on the right rivet. For car/desk flip the magnet around to get one or the other.
ANYWAY... here is my desk dock (multimedia station), made out of a Cup O'Noodles cup!! (like my friend said, if i waited one minute he would have been stoked - 4:20)