If you really need all of that I think I'd go with a separate object holding all of the options:
options = new SerializeOptions();
options.PrettyPrint = true;
options.Flag2 = "red"
options.Flag3 = 27;
serialize(someObject, options)
options = new SerializeOptions();
options.PrettyPrint = true;
options.Flag2 = "red"
options.Flag3 = 27;
serialize(someObject, options)