This object could be created using no VL just have to go in different direction for initial pick point. A entsel returns a pick point which may not lay on a line, but you can return that distance and work out where that point would be using polar and you know the angle of the line so know perp direction. Its just a math question using polar to work out points. Understand may give multi answer depends on line length.
Agree maybe Bricscad on MAC there are some comments re VLA function on MAC but nothing that can not be fixed quickly.
Re the dia select could use this needs 1 line changed to a known file rather than using vl-mktemp. Sizes are up to you.