I don’t know about OP, but when I put rope on my cat-tree’s soft-fabric column I just wound it around the column (cylinder, don’t know if it would work as well on a squarer support) as tightly as I could and safety pinned the bottom end to the 2nd to last row. The tight coil encourages friction and prevents slippage when he scratches it. The rope hasn’t moved, aside from when I rotate it for a fresher side, since I placed it over 2 years ago.