Here is how I disassemble my 58's and so far I've done it about 38 times in the last 4 months. Been cutting down the barrel, polishing and the like. Just have to put everything back together before I go to bed at night. Anyway I've included a diagram for you.

1. Take the grip panels off. (parts 44 and 45)
2. Take out the mainspring screw. (part 53)
3. Take the mainspring out by backing off to one side and sliding from underneath the roller. (part 20) the roller is part 25 under the hammer.
4. Remove the Cylinder (part 5)
5. Remove the trigger guard (part 26)
6. Remove Screws 37 and 38
7. Remove the trigger, the hand and the trigger spring. (parts 10, 12, 19)
8. Turn the revolver over onto its right side. Push the hammer down until you see the handspring screw (part 52). Unscrew it and slide the handspring out.
9. The Hammer can now be removed.