Rather than try to fit it in a box, you may well be better off wrapping the entire thing in layers of cardboard, bubble wrap, and a lot of packing tape then checking it in as oversize/irregular baggage. Unless there is some feature of anti-roll bars of which I am not aware, I imagine it is quite hard to bend it by handling it.

I doubt you will be allowed to bring such a thing into the cabin, unless you can persuade the staff that it is a novel sort of walking stick that you require.