Will great if the MAME menu appear when pressing the Hotkey & 2P button (or any other key combination)
You should be able to setup a hotkey of sorts, or align it with the RA hotkey. Just press Enter on the TAB field and then one button followed by a second button in quick succession. Actually it could be 3 or whatever. You'll just need to make sure it's not a key combo that RA is using to avoid two "actions" happening at once.