The picture is very useful!
You are right, you have to use a couple of smaller rope areas. (only two though!)
make the first one along the top of the step, and make the second one going down the step. Connect the endBody of the first rope to a block_box_mass_2 (found in entities>technical)
and connect the startBody of the second rope to this same invisible box!
Edit: Play around with the max-length of the rope. It should be about the sme as the distance between the rope-area and the posnode.
Also, shrink the invisible box down so it is approximately as thick as the rope