I saw where this question had been asked but never did find decent answers. I dont know if a tension style shifter would work, seems it could slide out of gear go into neutral and I wouldn't have any breaks. I want to use a stick style shifter as apposed to the thumb or twist grip shifter. The stick goes with the style of my project better. I have looked at the Sturmey stick shifters but they are sorta pricey when compared to others.
Theoretically, it seems that even if the shifter indexes and the hub is not in gear, the hub can still engage between shifter indexes because it is still moving the cable. So given that, one would think that you could figure out where the hub engages and move the indexes by making new holes in the plate or a new plate. Really, you could take the bearing out of the shifter and try it that way as the shifter would act the same as a tension shifter and not lock or index in place. I don't have the hub installed yet so I can't really say any cable length or test anything yet. I also cant swap the hub either, I have 28 spoke wheels and trying to find another 28 spoke 3 speed coaster brake hub is near impossible.