Hey there!
I haven't tried this myself and there are probably more qualified folks here in the forum, but copying and pasting from some other forum.
Fusion works slightly differently, but very nicely with a Wacom.
First thing you'd want to do is map your MMB to one of the pen's buttons.
Then, hold down the MMB and move the pen (hold MMB and hover over the tablet) for translations, Alt+MMB (hold MMB and hover over the tablet while pressing Alt) for rotation, and MMB+LMB (hold MMB and draw on the tablet) for zooming.
Moving and zooming work the same way for the Flow view.
Once you're used to that you won't want to go back to a mouse. It's a great way to navigate.
I hope this helps get your there. Let us know if this helps. If not, someone with some actual experience with Wacom table is lurking out there somewhere. 🙂
Thanks,
Nathan Chandler
Principal Specialist