Sorry, but analog stick supports keypad, it doesn’t work? You can set there any key you need and you can enable diagonals flag.
Edit : Aaaaaha, probably it uses number 7, 9, 1 and 3 for diagonals, right? You need 8 way joystick like has “Master of puppets”…Can you try first the virtual joystick? It works fine? If yes, then I can look at this.