Baccaman, the solution I usually employ when I want to make less than a pixel of movement for scrolling a sillouethe...is simply to selectively modify the sillouethe.
how can I explain it?......hm.okay I dont have to

see marco's shoulder there? it's transforming like there's no tomorrow. it's only supposed to be going up, but in order to make the movment more subtle than bumping it up a pixel, it's shape gets deformed as it moves up. in order to animate like this you need to have a picture of the sprite inside your mind which is more detailed than the actual resolution it's at, only that way you can modify it's shape and stay faithful to what it should look like, otherwise you're just making a blobbery mess.
am I making any sense at all?