compress the springs on the struts till the springs are bound tight to each other. Then mount your knuckle back on the ball joint, you should be able to get it on this way. if you push them together from the side(left to right/ right to left) the strut should slip into the knuckle. Grease the strut tube up a little and that'll help if you get close to slip in. It does work this way, it worked on my car and my friends SE sport. I don't believe in removing the knuckle from the ball joint..too much extra work.
