Manually. I chose line segments but it could have been circles, squares, boxes or donkeys.
I just dropped my shape onto the line and turned it to fit, which is why it is a bit rough.

I wasn't trying to replicate your line, just demonstrate a method that used Xara vectors instead of SWF or animated GIFs.
If it was just for this line I would have used HTML 5's Canvas.

The Xara approach doesn't require any other editor.

Acorn