Preface: I don't want anyone to go screaming into the night with their hair on fire looking to burn me alive while I'm sleeping.
I took a regular pair of vice grips and ground and polished all of the teeth. Butter smooth and shiny.
This made the vice grips not scratch the surface of the spring. It works really well. You have a very fine adjustment. Just like you would with a real spring vice.
When you go to release the pressure on the spring, open the vice grips SLOWLY. To not touch the adjustment screw. When you go back to compress the spring again, for installation, it will compress the exact same amount.
Easy. Peasy. Japanesy.
I've since bought a real spring vice for my bigger locks. It stinks with small Traditions mainsprings. Enter needle nose vise grips. Polished of course.
P.S. Let the pile on and kiwi kicking begin.