This hack is fairly easy to do for everyone who knows how to use a jigsaw and has a wall-facing 5×5 Expedit/Kallax.
– First figure out how you want the pathway to go (in our example we used only the leftmost two columns).
– Disassemble your Expedit/Kallax
– Cut the holes in the horizontal shelves with a jigsaw.
– After that cut the holes in the vertical smaller shelves.
– Sandpaper all the holes
– Re-assemble your Expedit and voilà finished!