@mistermikev, they aren't that hard, just open them up all the way then close them down to just where it will clamp. That way I was ready to apply them right after I put the glue on.
I got them on Amazon, but they weren't cheap, almost $20 each. But that's a small fraction of the cost to have a luthier do it. I made some cauls for the top of the bridge but these clamps wouldn't open up enough to use them, with cauls on the inside,so I just used some leather to protect the surface of the bridge. I also super glued some small wooden cauls onto the bottom of the clamp so they wouldn't dent the bridge plate. I probably didn't have to do that, but I did anyway just in case. That's the reason the clamps didn't open up enough to put wooden cauls on the top.
Thank you.
Ron