Attached is my first attempt at creating a max object that can rotate an image and can therefore be used to rotate a knob given a single image. I used the jsui_imagestuff.js example for guidance.
I am not a graphic expert. The knob is a bit wobbly because the photo image I snarfed from Moog's website was not originally taken directly from above. I assume that this could be fixed with a little photoshop perspective transformation.
The knob can accept a message called scale that both specifies the min/max range of the knob as well as min/max output values to be produced as you turn it. You can also feed numbers into it to make it rotate.
The only thing I don't know how to do is to make the background transparent so you can place the knob on a panel properly. I'm hoping that someone with opengl chops can tell me how to fix this.