I realize this is a bit old, but since I still found this via google, here's some newer information that I finally found elsewhere, for anyone else who lands here:
3DXWare 10.4.10 is the last version which unofficially supports the SpacePilot.
10.4.10 happens to be Windows 10 compatible natively. Unfortunately, since its support for the SpacePilot is unofficial, it doesn't get listed when you open the archived drivers page to the SpacePilot. It does show up for the SpacePilot Pro. This works! While the listing can only be found under newer products like the SpacePilot Pro, what you download is not specific to only a Pro and will still recognize a SpacePilot.
So here are the steps:
Go to the archived drivers page
Select the SpacePilot Pro from the Product dropdown.
Pay attention to the version numbers! You want "3DxWare 10 for Windows" (64-bit or 32-bit) version 10.4.10. Release date is 03/23/2017.
Install it normally.
There you go, it should just work (including the display staying up to date with window selection), although you may need to reboot or at least restart software before it works properly in everything. This is in Windows 10 Pro Version 1803 (2018 Spring Creators Update).