I've taken apart a set or two of cross spoke wheels and I can tell you it is kinda a pain in the ass. If the spokes are old, you end up having to cut them off - and not with bolt cutters, but with a angle grinder. Reason being is that the spokes won't want to slide back out of the rim after they've gotten cruddy with years of rust / oxidation.
However, I'd say do it at least once just to see how they go together. It's kinda a fun project to do once.
1964 LI125S with a 240 MRB kit