A dumpit reveals.
Coordinates = (158.0 220.0 0.0 234.0 220.0 0.0 234.0 310.0 0.0 284.0 310.0 0.0)
So just a guess use entsel this gives a pick point, you can then find the segment so pick next point rework out the co-ords of the 2 adjacent points and update the leader co-ordinates.
Will have a play but some one else jump in if you have something. I have some where pick pline segment which is needed.