Similar kind of tool you get with a kids full sized trampoline iirc.I had exactly this problem a few years ago and only remember the struggle, not the success. But when I was at Billing recently I remembered this struggle when I clapped eyes on a tool for the job on one of the tool dealer stalls. It's a T handle with a hook on the end, about 1/4 dia rod, and sturdy enough for the job. I bought one because if I ever do that job again, I'll be thankful that I've got it to try.
I guess that is to attach the springs with the shoes in position. Might be easier. My method was to assemble it all, three ends will fit into the slaves easy enough, then the water pump pliers to heave the last shoe end in..Retrieved it from the pile of stuff awaiting to be put away. It's made by Silverline. Name is Spring Hook 153mm. Part no 416746
I guess that is to attach the springs with the shoes in position. Might be easier. My method was to assemble it all, three ends will fit into the slaves easy enough, then the water pump pliers to heave the last shoe end in..
What's happened to the OP anyways??