If the box with the time running up to 2.000 at the bottom of the screen shows up in the middle you press Button 3, on the left Button 1, on the right Button 5.
I actually played on one of these in Buffalo one time. The buttons are lined up underneith where the boxes are. In MAME, it's not so obvious, but once you get an idea where the boxes appear, it's a snap.
I've been playing with A, S, D, F, and G as the 5 buttons, except for Brick Break and Rush Hour, which I use Keypad 4 & 6 for slow left and right.