first you need a 'special tool' a 45-60mm jubliee clip - a decent quality clip is essential. Drill a hole in the clip thats just a touch bigger than the spring and the ball.
next, get your hub and satisfy your self that its unworn and the inner is fitted the right way - the larger step in the inner always points the same way as the larger step in the outside. Also make sure that the gaps are lined up correctly on the inner and the outer.
now push the inner outwards so that the jubilee clip can be slipped over, it should be just slack enough so that it can rotate around - if its a new clip you will probably have to keep adjusting the size through out this process until the clip is the 'perfect' size, once its sized you wont have to adjust it again. Next, line the hole in the jubilee clip up with the hole in the inner and slip the spring, then the ball in, then rotate the clip round to the next hole and repeat. Its best to fit the springs now, rather than before the jubilee clip as it stops them getting caught in the edge of it when you drop it on.
once all three balls are in place, rotate the jubilee clip so that the 'saddle' part is covering one of the detent balls - this is important as the clips are never quite 'round' and this is the tightest part. Then lay the hub flat on the bench and push the inner down, it will only go so far as the balls will prevent the inner going all the way in.
now take three small flat bladed screw drivers, push then down the jubilee clip to press the balls further in, i use a smaller one against the saddle of the clip and two slightly larger ones against the two other balls
if your clip is new, you may need to adjust the size to allow the screwdrivers to push the balls in enough to defeat the outer, or slacken it a little to the inner can slide.
now push the inner with your thumbs and it should 'pop' into place, you may need to jiggle the screwdrivers about a little, or use the shaft of a hammer to lightly 'tap' the inner home. if you need to use anything more than very light force then you havent pushed the balls far enough home with the screwdrivers to allow them to pop past the lead in on the outer race.
with a bit of practice (and once your clip is the right size) this is a two minuite job
before you know it you can have done loads of them.......
took to doing it in the bathroom then with the plugs in the bath and sink so as there were less places for it to get lost behind 
thank you for sharing this system.
