Ken - I learned a few weird things along the way, but I'm not sure I have a solution for everything.
First things first - what I modified was the P1 Left and p1 Right settings. I selected them and moved my spinner the direction I wanted (counter clockwise for left, clockwise for right). See the picture for the results. I don't think you can modify the sensitivity, but fortunately, it plays very well, so I don't have a problem with it.
Some weirdness I learned.
First, I'm using version 2.40 and it wouldn't recognize my TurboTwist2 for these inputs. It would recognize if I wanted to change other settings, but not P1 Left and P1 Right. I hooked a mouse up to the system, and it didn't recognize inputs from the mouse. I tried it on a different computer and it recognized my mouse inputs, so I was able to set it up.
I tried Mame version 2.38 and it worked fine with my TurboTwist2, or the mouse.
I tried Mame version 1.05 and nothing worked.
So I'm not why it was acting like that. Could be user error, or something with the mice I was using, or something in Mame. I didn't keep testing after I got it configured. So, the advice I would give is to try to configure those inputs in Mame and if your version of mame or hardware isn't doing it - try mixing things up.