Based on 9 years driving the NSB versions for real, they should work like rasender-roland describes. The Norwegian El-11 and 13 have a nullstellung, then you increase, and bang-bang-bang like the knallfrosch. Return to null and you keep those Stufen. To decrease, anticlockwise (reduce). Our El-14, which was based on the Ae 6/6 the same thing, but instead of a Hebel, a Wolkswagen steering wheel
- and a luftmotor to drive the knallbreakers.
EDIT:
Need to correct myself here:
The locos work correctly. Me, I have no control when I can't hear the switching (like in the real-world locos), and I also loose control when there isn't a meter showing the actual Stufe. So Dot is Neutral. M is regulator slow up, + is fast up. Minus regulator slow down. After setting off like a rocket from Innsbruck with the Lion, I was able to control my speed quite precisely, almost like I had an AFB. Best thing is to not use the HUD, just watch the Hebel. Up for two secs, back to Dot. Down (-) for two secs, back to Dot.