If you are in south Italy: Autosole A1 to Firenze; Firenze Mare A11 and finally Livorno Genova A12. If you are in North Italy: Autosole A1 to Parma; Cisa A15 to Santo Stefano and finally Genova-Livorno A12. The highway A12 exit : Viareggio/Versilia
International Airport in Pisa (only few kms far); by the airport you can reach Versilia by taxi, bus and train. They will take you directly in Versilia even if they will also stop in every important place.
Line : Genova-Parma-Bologna
Line : Livorno-Milano - Station of exit: Viareggio