First, flatten the end of an annealed 20-gauge wire. Insert a reversed 1mm drill bit in the flex shaft and place the flattened end of the wire into the slot in the chuck, next to the drill bit and deep enough to hold it securely. Then turn the flexshaft (really slowly!) while holding the end of the wire taut to wind the wire around the mandrel.
Remove the coil from the mandrel, hold it securely in a ring clamp, and saw along the length to cut all the jump rings apart evenly.
Flatten each jump ring with parallel pliers, then close the gap by squeezing the ring with chain nose pliers on either side of the opening.
Don't bother to fuse or solder the jumpring, just place it onto the back of the earring (flux everything) and add a ball of easy solder to the interior.
Hold a length of 20-gauge wire to form the post in crosslock tweezers while gently heating the earring, jumpring and solder. Position the post nearby but out of the flame, to keep it from overheating. As soon as the solder melts, pop the post into the jumping and hold. Then cut the post to length and finish the end with a cup bur.
To see a live demo of the soldering process, check out Ronda's video.