For MAMEWAH just hold in '2' for 3 seconds...it will 'disable' the setup menu. Just hold in in again to enable.
I have been struggling with the 'shift' feature as well...it works fine for ME...but friends...well, friends are idiots and have no idea what is going on...they like to press buttons...repeatedly

As stated, you may not even need it, but if you're like me and enjoy doubling your cp button capablities, just make a dedicated shift button, and hide it under/behind the cp. This way, you can make ALL the 'emulator/front-end' keys shifted buttons, so your friends can't use them...unless they find the magic button. Even if they do, it does nothing on it's own.
Instruction card is a must if you want people to plug and play. I need to make one myself...it's just I don't really have a lot of room with a 27" monitor. What do I do, staple it to the marquee? Make it a kick plate? Hehe. There is a bit of room right below the screen and above the cp.
And for the coins, disable the buttons and make them pay
"I put a quarter in and the games disapeared!"
"Aww, that's too bad...you have to put 5 more in to get back to the game list"
