I doubt that opendbcopy will help you to create a convertor. That software appears to just copy data from one database or column to another database or column possibly changing the database type or column type. A convertor for converting from one bulletin software to another bulletin software needs to do more than that. A convertor needs to reformat some of the data. Bulletin board softwares generally store the data, particularly message posts, in different formats. This is because of the differences in the way the boards handle markups (bbcode tags, etc).
To create a convertor, the best way is to use the Unified Convertor Framework which comes with phpBB3 as the phpBB2 to phpBB3 convertor. Basically, the phpBB2 to phpBB3 convertor is modified to suit the software you are converting from by specifying where to get the data from and reformatting it as necessary to fit the phpBB3 requirements.
Have you hugged someone today?