There might be an option in TomTom Navigator to convert between OV2 files and ITN files.
Convert TomTom Navigator point of interest data to TomTom Navigator itinerary data.
We have found one software suitable in our database for this conversion.
Windows Mobile/CE software - convert ov2 to itn on Windows Mobile
A popularGPS navigation software for Windows Mobile and Windows CE based devices
Convert from ov2 file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.