I would have sworn that there was a TP specific data source, but as it turns out, I don't find any on my system either. It must be using the generic Access source.
Maybe you can temporarily turn on ODBC tracing and launch TP to see which username, password, etc, it is using to access the database, and then use those through a data source of your own? To see the database structure (if you don't have MS Access) I recommend MDB Viewer from
www.alexnolan.net (it's free. In the File Open dialog, enter *.tpdb8 to find and open your database).
Several users in the past have made web applications that use their database and have written about it in the old newsgroups. If I remember correctly, a few even posted .asp or .net source code. If that might come in handy and you have newsreader software, see this post for a link to the newsgroup archives:
http://forums.cerious.com/forum/index.php?id=1426. All info will pertain to TP v7 and earlier though, and there have been some major changes in the database format since.