In the pelican parts "how to adjust your valves' article they make use of this feature to make it so you don't have to keep getting out from under the car. They say to roll up on 1 ramp only and then jack up the other side, so you'v'e got room to work under there and then the 1 wheel is held stationary.
I guess it's a little different since you're in neutral and to do this all you have to be in a gear, but if you turn the free wheel from under the car (that's the point, to be able to stay under the car), you're then turning the engine. If you think the one wheel spinning is weird, what happens if the other wheel isn't held stationary is even weirder, as it will spin in the opposite direction! I've always thought that was just crazy.
Honestly that seems like a retarded way to adjust your valves, as you'd have to drive off after the first side, and set it up the other side to do the other.
I guess I've never had the pleasure of adjusting valves in a 914 though, as I've never actually driven mine.