whenever I have to remove the CV axles or the transmission out of my Mitsubishi eclipse I have to take the nuts off  of the ball joints. well once I have done my task and I begin to reinstall everything,  I used to run into a problem that will bother me all of the time until you figure out the solution. the problem is the ball joints that spin when the lock nuts are being reinstalled. A simple solution to alleviate that problem is to:

get a floor jack Preferably the small 2 ton hydraulic jack but others may work.
1. place the jack directly up under the ball joint that you are tightening up
( if the car is too high I place a small 4×4 block of wood on the jack to make up the difference. While using that wood I may have to ad

if I am working on a soft ground I put a piece of wood under the jack to keep it from sinking in the ground.)
2. extend the jack until the maximum amount of pressure is on the base of the ball joint.
3. once you get the pressure on the ball joints install your lock nuts and the ball joint shouldn’t spin anymore and the lock nuts should install as presumed.

DISCLAIMER: Do these repairs at your own risk Im not responsible for your actions