How to get KEYCODE_MEDIA_PLAY_PAUSE keyscode events in android?

I'm trying to get the media keycode events in android. aka KEYCODE_MEDIA_PLAY_PAUSE (keycode 85). But these are not defined in unitys keycode enum. Below are the things I've tried that failed. Does anyone have any other ideas?

1) Can't add to, or overide KeyCode enum such that the following would work. And can't change or override Input.GetKeyDown.

         if (Input.GetKeyDown((KeyCode)85))
         {
             Debug.Log("KEYCODE_MEDIA_PLAY_PAUSE :85");
         }

2) Created an android plugin that uses onKeyDown to store keyevents. The problem here is onKeyDown is implemented in View or Activity both of which are not running in a compiled library. Below is the onKeyDown function..

 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event) {
     Log.d("KeyboardTest", "onKeyDown: " + keyCode + " , " + event);
     LastKeyPressed = KeyEvent.keyCodeToString(keyCode) + "";
     return super.onKeyDown(keyCode, event);
 }