Use whatever inputs you want and map those as exit and pause in MAME/HS.
Thanks Nep for responding! I know the ipac can use a combo of buttons to achieve this right out of the box. For instance, something like hold up on joy 1 and press button. And I understand what you're saying, how you can just set it up in Mame/HS. But what if all my inputs are taking? The only one's left are the controller inputs, as I don't use them (joysticks are direct USB). So could I just use those Up, down, left, right, inputs you think? Thanks again!