I don't see a way with reflector, or in the Arx docs, as the way you would do it in lisp, it doesn't look like you can with C#. Lisp would be
(vla-get-SupportPath
(vla-get-Files
(vla-get-Preferences
(vlax-get-Acad-Object)
)
)
)
You can get an object, from the Application object, for the Preferences, but I don't know what you can get from there.