Uhrwerk@ hehe, it's still a bit dirty for me, but I guess I got the idea (I got it to work anyway).
If you want to give it a try, here is a small demo (it's 7 kb made with the code from the first post):
c_move result test thing
First value is the covered distance, second one is the moving speed.
Just change the fps_max at run-time to see what I was talking about.