This, and you can also squeeze on the spring with the other hand to get it started compressing, much easier to hold the spring once it is compressed with one hand than to compress it.

If you still can't set them by hand, when I was a young kid and got my first 110s, before I could set them myself, my dad made me a couple "safeties" out of some hard wire, it was about the size of 9 wire but very stiff and I think he bent them in a vice. Anyways they were hooked on both ends instead of having one end crimped around the spring. I could compress them with a rope like oh trap describes, then put the "safety" on the spring and then set. I was setting 110s by myself this way before I was 10 years old.

Use a safety gripper too on the jaws until you get the hang of setting the triggers with your fingers out of the way.