After discussion with the developer of TKMon, I learned that the command
syntax is actually Stockade123456
LonTopLeft,LatTopLeft;LonBotRight,LatBotRight    The latitude and
longitude will be sent as positive numbers with a NSEW suffix. (E.g
50.2345N, 12.2345W).  Example is stockade123456
123.132883W,49.140941N;123.131509W,49.140041N