How to bend hard plastic tow cables from old kits?

I would try and soak the item in hot water for a few minutes which should soften the plastic and then bend it into the shape you want.  A hair dryer may work but you have to be careful not to over due it that it starts to deform the existing shape.

I would cut out the "wire rope" section out and just keep the shackles. I'd take a piece of copper wire, multi-stranded and make a wire rope out of it. Much nicer and can be bent as you please. On the other hand I have heard that the tow cables are very stiff and fight the tankers all the time, so that they basically go where they want to, and not where the tankers want them to - so maybe what you have is a faithful representation of the real thing... Anyhow - good luck with your build and have a nice day

Paweł

I second Pawel's suggestion; cut the eye loop ends off and use either wire or string like Tamiya often provides for their kits.

You treadheads might be interested- some vendors are now making really nice 3D printed chain for ship models in the larger scales. Probably wouldn't work so well here as all hulls have a different sort of drape, but interesting...

Tanks, AFVs, and soft skins don't use that much chain. At least not for towing one another. Cables are much more common for towing purposes. 

I also like to use real wire for the tow cables. Some twist ties(usually come with new electronics or garbage bags) work well. 

As stated above, cut the shackles off, drill them out, and use three or four wires twisted together with a cordless drill. 

Its simple and provides a much more realistic look. You can bend them any way you want.