Assuming you already setup the GamepadManager just add:

//near the top of App.cpp
#ifdef PLATFORM_WINDOWS
#include "Gamepad/GamepadProviderDirectX.h"
#endif

//Add this to actually init the gamepad(s):

#ifdef PLATFORM_WINDOWS
	GetGamepadManager()->AddProvider(new GamepadProviderDirectX); //use directx joysticks
#endif

Oh, you'll need to link against DirectX of course, specifically dinput8.lib and dxguid.lib. Will work on directX 8 and newer I believe.