I don't think anyone working for Simplify3D reads these...
I opened a support ticket after posting here, and was quickly provided an openssl library file for my system which I could drop in the Simplify3D folder which fixes the problem.
There is an opensource (BSD license, so fine to use in commercial software) library available called libspnav (http://spacenav.sourceforge.net/) which you can use, which should make implementing this not all that much work.
Note that there is an opensource library which you can use for the implementation called libspnav (http://spacenav.sourceforge.net/), it is available under the 3-part BSD license, so it's perfectly fine for you guys to integrate in simplify3d!