Now that I think about it(yes, I can think) I'll just wire the vertical optics electrically to where the horizontal optics are. Then I won't have to do any mounting or anything, just solder a few wires.
Yes, you can do is. Quick and easy hardware solution.
Analog+ can reassign mouse's axis, so you could assign mouse Y axis to the game's player 1 X axis, but it would only work in Analog+.
A very few mouse drivers can reassign the mouse axes for windows, which should also effect mame. I don't which drivers, though.
If I was you, I'd go with the hardware fix. If I was me (hey, I am me

), I'd do the Analog+ way.
