Not sure if I understand where precisely you are having trouble (electrics or software) but if you are trying to get the camera to determine best focus via Max, something like jit.sobel -> jit.3m (Higher mean values should indicate better focus) might help.

i`m trying to adapt an autofocus to my projector, so to do this i disable the casio xj-140V and rewire the connection of the focus len`s motor, so now im trying to put an camera outside the projector which is wired via max/jitter to capture the image from projector and by the way max would interpret the image projected and then adjust the motor lens. i really would like to realize this via max, but i don`t know if its possible. very thankyou