I have no idea how to set the exact pulse width on the signal unless you have a hi end ocilliscope or some other hi end meter that can measure pulse width. I dont know of any cheap ones.
Is there any way with your gear to measure pulse width or to figure it out by trial and error?
I know that with the servo throw set all the way to one side is the low pulse width = 1000 and all the way to the other extreme is the hi pulse width = 2000 - but I have no idea which way is which. I would assume negative settings are to the low end? I also know that center position is 1500
It looks like all those steps are 130 ms apart. It would probably work if you set the 3 position switch to give you the first three 130 ms steps in order.
Lets see, If Im doing the math correctly, the folowing may work - or at least get you in the ball park.
If full throw to one end is -100 (Im guessing thats equal to 1000 ms pulse width) on your end point or travel offset screen, then Id try -71 for the first step and -43 for the second step (middle position on the 3 position switch) and -14 for the third (the final position on the 3 position switch).
Then id set the 2 position switch to give an offset of (Im guessing on the plus direction. It may need to be negative) +0 in the default position and +85 in the second position.
Lets say both switches start in the down position. That is the -71 on the 3 position switch and 0 on the 2 position switch.
In this position, the total offset is -71+0 = -71 which, if my guesses are correct, should give you a pulse width close to 1165.
Moving the 3 position switch one step to the middle position will now give you -43 or somewhere near 1295.
Moving the 3 position to its last position should give you -14 or about 1425.
Now, if you move the 2 position switch to the UP position it adds +85 to the value already set by the 3 position switch. So if you move the 3 position switch back to the starting position it gives you -71 again and the 2 position switch adds +85 which = +14 or about 1555.
Now leave the 2 position switch in the UP position and move the 3 position switch to the middle and it should give you -43 + 85 = +42 which should be near 1685
The last positions should give you +71 or about 1815