That version of MAME is so old I don't know what it supports. However, if memory servers me correctly, the U360 is just a joystick with 6(8?) buttons. The instructions should tell you which "pin" is which button number. Mame, should be set to use button 1 and <ctrl> as the same thing (I think it's ctrl). Anyway, it should be seen in the OS as a joystick button, so you should be able to verify the buttons are working in the OS before trying in mame, if you haven't already. If mame is not responding to it by default, you may nee to map the "general" or game specific input to that joystick button as appropriate (i.e. JoyBtn 1 to player 1- button 1). I don't think you need to change anything in the mame.ini to enable a joystick, but not sure about that version of mame.