It will be similar in design to this except the bearings wont have a retainer (loose ball).............or at least they didn't on my OS Skyway coaster Tuff II
When you reassemble then pack a load of grease on the bottom bearing run and stick your bearings in it then run the axle fully through so the bearings can't escape then place the axle on the floor/desk etc, etc so the axle stays put and then the other side just drop the bearings past the axle which will have loads of play because the hub externals haven't been screwed down yet.
Just make sure your pawls are the right way around and aligned. If they aren't then you wont be able to fit it. So you'll know when you've done it right because it fit!!