Thank you very much, Hashbox for:

Changed the public IsAdministrator back to protected, 
now checks Config to see whether it is allowed to run or not. 
Defaults to false (not allowed).
To use add the following to OpenSim.ini
[LL-Functions]
AllowosConsoleCommand=true

OpenSim/Region/ScriptEngine/Common/LSL_BuiltIn_Commands_Interface.cs

@@ -641,6 +641,6 @@ namespace OpenSim.Region.ScriptEngine.Common
         int osTerrainSetHeight(int x, int y, double val);
         int osRegionRestart(double seconds);
         void osRegionNotice(string msg);
-	int osConsoleCommand(string Command);
+	bool osConsoleCommand(string Command);
     }
 }