I use zsnes, fusion and mame. I mapped the emus to my ipac configuration, not the other way round. I found it really easy tbh. Each one has some kind of controller config. Just press the button on your joystick when you are prompted. So, if it asks what key you want for ACTION, press the button on your joystick that you want as your action button, and you will see the keystroke appear that you have for chosen (in Winipac for example) for that particular button. Make sense? Not sure about other emus tho. I know Winuae is a pain in the butt for key remapping.