Flavio has commented on my post of the 1st June (below in blue) and also on the CTC Eurovelo 5 forum (below in red) with the following messages;

Hi Andrew,

Great project! I found it only today.. two years later For the question posted in August, 6th… 2008, the return, [don’t know if it’s still waiting a reply], I suggest the train. It will need some days, but you can surely have a nice trip. I did big returns across Europe by bike+trains. Look for example here to find timetables (in advanced options mark the bicycle transport). If you need help, please email me. I will do the opposite way in the next July, from Italy to North Sea, but with a shorter total distance. Hope we cross somewhere… at least with the thought. Have a nice trip!!

No there aren’t national cycle routes in Italy. Unfortunately the maps you reported in this page (“Bicitalia” etc.) are only dream maps. We haven’t long distance cycle routes, and probably we won’t have them for decades
However, there is the Trentino Alto Adige region which works hard to build a network of cycle routes: now it is at a good stage, almost completed, and it is excellent
Some other regions (I heard about Veneto, Marche, Abruzzo, Liguria) are building other projects, but are actually disconnected from Europe.
So if you want to reach Italy via cycle routes there are only few possibilities; I know these:
Resia pass
Brenner pass
Val Pusteria
The first one is the most connected with European cycle routes, and it can arrive to Trento or Mantova via very good paths. You could for example take a look at my tours, almost all along quite cycle routes, which are shown here.
I didn’t arrive in Mantova, but you could (I suggest: Trento – Mori – Torbole – Riva del Garda – ferry boat – Peschiera del Garda – Mantova; this is all along real cycle paths).
To proceed further towards South, if you want small and quite roads, you’d need to study very detailed maps with attention, accepting a lot of ‘waves’ in the itinerary (both horizontally and vertically). I know Mantova – Modena should be easy (with unpaved roads), then from Modena to Appennini mountains there are some signed cycle paths, but then… you will be completely alone with your map.
Around the Via Francigena project there are probably other ways suitable for safe cycle touring, or they will be, but till today I didn’t hear anything of complete about that…
EDIT:
Ah… I read just now about your short preparation for this tour… well, I looked for the first post of August 2008 but it seems so deep to be unreachable… so you already planned all the Italian roads, and my suggestion arrives with a certain delay.
Well, I think you’ll find a bit of traffic in your way. Ride carefully!
EDIT 2:
If you still need good cycle maps, dedicated exclusively to cycle touring, with the complete road from North Sea to Trento via Rhine – Lake Constance – Resia Pass, they are the same I bought for my tour. So tell me and I’ll send all the titles.

Thanks for all the information Flavio. You can read more about Flavio on his website which is dedicated to Grandride which he defines / explains as follows;

“Grand Tour” is the ancient name of a long and slow trip across Europe, which was effected especially in the centuries from XVII to XIX, and which went on for months or years and had as aim the cultural growth of the traveller through the knowledge of different local cultures. The traveller had all the time to identify him/herself in a place, and elaborated his/her own synthesis which was getting rich with the passing of crossed lands.
“Freeride” is a contemporary sporting concept, introduced in the last years and applied on some sports of movement, which privileges “…contact with nature, wide and free spaces, fun, importance of group in some cases, making agonistic and competitive aspect secundary” [from Wikipedia].
This website introduces a new type of bicycle touring: the “Grandride” cycling, which is given by the union of Grand Tour and Freeride.

You read about it first here!