You don't need extra tools Ian. Just a 2mm pin to release.
You can get set lengths of pre eyed lanyards, with the wire ends soldered. Or if your adept enough you can cut and crimp you own.
Just add the gripple and go. Yes they are similar to the fencing types but if you source them from a good supplier and not CEF, they are cheap as chips.
Adjustable, removable etc.
The tools on the link are for tensioning wire rope. I could have narrowed it down to particular products but as I have already said, if anybody has anything about them, they will work it out to suit their own ne