I'm thinking, would it be possible to create an effect that resembles such a cable launching from a unit's jetpack, going up, when the jetpack is activated? And then, would it be possible to have the jetpack only go up and down, via some odf coding?
Would probably look very unconvincing.
A second possibility: take that cable weapon from the snowspeeder. I remember a while back someone said you can't give it to units. So why not to vehicles? Is a "grapple car" possible?
The thing you have a picture of is a cable car (moves along set path), and the cable harpoon only latches onto AT-ATs.
Look, it's pretty much impossible to do. Plenty of people have tried. Mav's done it through lua scripting, and lots of it I imagine, rather than weapon odfs. It isn't possible through odfs.