There is a tool that looks like a big C-clamp that is made to remove and install ball joints, but I don't know what they cost?
I am not familiar with the "Trick" however many ball joints require a hydraulic press, which is basically a hydraulic jack with a heavy metal frame. I imagine the Trick is to use a hydraulic jack and some home-made metal frame in conjunction with using a fixed part of the truck's frame??
A simple benchtop hydraulic press can be made from a hydraulic jack, some channel iron 1/4" to 3/8" thick and some very strong bolts to make it adjustable for other uses. If you only need it to press in ball joints, you are better off just taking the A-arms to a shop and paying a few bucks to have them pressed in.
If the Trick involves pressing in the ball joints with just a hydraulic jack and without removing the A-arms, then that would be great?
You might want to do a web search to see if this trick is explained anywhere.
...Rich