According to Trenitalia site (in Italian only): http://tinyurl.com/amxcn

The only available option is to have a porter meeting you at the departure station and another one waiting for you at destination. The service is available for Eurostar trains only and between selected stations (Rome and Florence are included). The cost is 5 euros per each porter and it must be booked in advance calling the Trenitalia number 892021 - voice option 6, once you have your Eurostar ticket in your hands, as you need to supply full itinerary details and a ticket number. The departure meeting point can be agreed upon calling (I suppose it must be inside the station area or surroundings) while the arrival meeting point will be at the platform in front of your car.

Hope this helps.

Bye, Paolo Trieste, Italy