From my Kuzma tonearm manual -- the most complete and helpful Owner's Manual I have ever seen:
(1) remove tonearm from TT, place upside down on a work table.
(2) remove cartridge.
(3) remove insulation sleeve from pin connector.
(4) insert small nail or drill bit into pin connector--exactly how cartridge pin would insert. This prevents overheating of the connector and stops solder from entering connector.
(5) fix nail / drill bit into a blob of blue tac or other material to hold pin in position and securely to the table. Nail / bit can also be placed into the chuck of the electric drill itself. The objective is to get connector secured and raised off the work table so step (11) can be executed.
(6) gently pull about 20-25 mm of wire from tonearm and use sharp knife (exacto or razor) to carefully strip about 3-4 mm of insulation.
(7) with clean solder tip, melt any solder left on pin connector and blow away from hole.
(9) put plastic insulation tube on wire.
(10) place stripped end of wire thru hole in connector and bend back forming a hook to secure.
(11) from underneath place soldering iron tip, and from the top the solder.
(12) slide insulation tube over solder joint. Gently remove pin connector from nail or drill bit.
This is a simple and effective solution that costs nothing, and requires only one set of hands!

Owner's manual is available online. See page 21 for complete instructions and illustrations:
http://demo.amplio.si//AmplioCMS2/UserFiles/File/29/stogi.pdfGood luck.