Found 2 DirectInput devices:

0: 'Keyboard' axes: 0, hats: 0, buttons: 256 (buffered)
   1: 'Mouse' axes: 3, hats: 0, buttons: 8 (buffered)

So let's get this straight:
Left, Right, and Middle clicks work.
Wheel Up and Wheel Down work.
X/Y axis doesn't seem to work yet.

src/InputMapper.cpp

@@ -559,9 +559,7 @@ void InputMapper::AutoMapJoysticksForCurrentGame()
 	vector<InputDeviceInfo> vDevices;
 	INPUTMAN->GetDevicesAndDescriptions(vDevices);
 
-	//
 	// fill vector with all auto mappings
-	//
 	vector<AutoMappings> vAutoMappings;
 	{
 		// file automaps - Add these first so that they can match before the hard-coded mappings