Not that easy. Ruger won't provide nor install any part so that the end result is that of a non-cataloged model. There were no cataloged convertable Vaqueros so they won't provide one.
Best bet is to find a 45 ACP cylinder from a Blackhawk convertable and hope it tmes up correctly or have one made.
For the .40 S&W cylinder...might me able to find one of the few convertable vaqueros that had cylinder chambered for that cartridge but it's not too likely. Again, gonna need to get one made. A thought though...can the .40 S&W be used in the 10mm cylinder like the .38 special is in a .357 mag chambered one?