Thanks Frank for the fast reply!
I've seen Theo's videos and he is a genius (he has lots of tools besides his obvious talent..). One thing that worries me about the displaced axis approach is that maybe with a rotary switch (instead of rotary encoder) the displaced gear will slip as it has to overcome more friction from the current detent. I think encoders generally offer less resistance to turn than rot switches but I'm new with this so i'll give it a try.
I thought of the "push and turn" as a software alternative to this (although it won't be like the real thing!)