replying to myself as I meanwhile found a way to install the NT4 driver for the pen/panel: Use the 3500 driver instead, make sure you find the file called
and follow the .doc file that is included.
Basically, installation is not done via the .inf file (do not right-click/install the file), but via Control Panel / Add+Remove Programs / NT Setup tab. Who would have thought of such a way???
Well, it does not seem to work with the 3400 versions of the drivers, though. But the 3500 drivers do work fine for the 3400 unit.
Hope this might help someone (though I'd doubt anyone but me would ever want to go back from 2k to NT4...)