Here's the easy way. Make a minor investment in some Mortite (plumber's putty) or Fun-Tak. Take a small hunk of it and roll it between your fingers until you end up with a cylindrical piece that's maybe an inch long and a quarter-inch (or less) in diameter. Use this to pick up the nut and hold it onto the end of the screw and then turn either the nut or the screw until the connection is made. A little practice and you can do this in seconds. Good luck, Dave.
Tips to install cartridge
I would appreciate any tips you seasoned vinyl-o-holics may have to start the tiny nut on the tiny screw when mounting a new cartridge other than putting the nut on top of the arm and or to somehow secure the cartridge from falling while installing. I don't want a new investment to go flying off my fingers. Thanks.