well, I'm in over my head on this one, but this should be somewhat of a start

src/archutils/Darwin/MouseDevice.cpp

@@ -0,0 +1,24 @@
+#include "global.h"
+#include "MouseDevice.h"
+
+bool MouseDevice::AddLogicalDevice( int usagePage, int usage )
+{
+	// Mice can either be kHIDUsage_GD_Mouse or kHIDUsage_GD_Pointer...
+	// Let's just go with kHIDUsage_GD_Mouse for now.
+	return usagePage == kHIDPage_GenericDesktop && usage == kHIDUsage_GD_Mouse;
+}
+
+void MouseDevice::AddElement( int usagePage, int usage, IOHIDElementCookie cookie, const CFDictionaryRef properties )
+{
+	if( usagePage != kHIDPage_GenericDesktop )
+		return;
+
+	DeviceButton button;
+	if( UsbKeyToDeviceButton(usage,button) )
+		m_Mapping[cookie] = button;
+}
+
+void MouseDevice::Open()
+{
+	// I hate coding blind...
+}

src/archutils/Darwin/MouseDevice.h

@@ -0,0 +1,20 @@
+#ifndef MOUSE_DEVICE_H
+#define MOUSE_DEVICE_H
+
+#include "HIDDevice.h"
+
+class MouseDevice : public HIDDevice
+{
+private:
+	// stuff
+
+protected:
+	bool AddLogicalDevice( int usagePage, int usage );
+	void AddElement( int usagePage, int usage, IOHIDElementCookie cookie, const CFDictionaryRef properties )
+	void Open()
+
+public:
+	// even more stuff
+};
+
+#endif