Portoferraio can be easily reached from Piombino Marittima (Tuscany coast) either through jetfoil (40 min) or by ferry (1 hour). Four sailing companies are available: Toremar, Moby Lines, Blu Navy, and Corsica-Sardinia Ferries. Portoferraio downtown, the conference venue, the restaurant of the conference dinner and the recommended hotels are located at a walking distance from the pier.
From Pisa airport: take the People Mover service that connects the airport to Pisa main train station (Pisa Centrale). The service is available every day from 6:00 AM to 00:00 AM at 5/8 minute intervals. From Pisa Centrale take a Trenitalia regional train to Piombino Marittima (around 1.5 hours).
From Florence Peretola airport: take the tram T2 (timetable) from the airport to Florence main train station (Santa Maria Novella). From Firenze Santa Maria Novella take two Trenitalia regional trains to Piombino Marittima (around 2.5-3.00 hours).
Alternatively, from Milano Malpensa international airport, take the Malpensa Express (timetable) to Milano main train station (Milano Centrale) and from there a fast train plus one or two regional trains to Piombino Marittina (around 6 hours).
Trenitalia timetables are available here.
Car rental offers you the opportunity to drive across the beauties of Tuscany. You can rent a car at Florence and Pisa airports and then drive to Piombino Marittima to catch the ferry. Many car rental services (Hertz, Avis, Budget, Europe Car, Golden, Maggiore, Giuliani . . . ) are available at both airports. Check out this link.