Due to lack of interest, development of the GUI version of portdrvr for Flight Simulator X^® has ceased.  The alpha version is available here and is offered without support of any kind.  It is mostly functional on 2 axes, but documentation was never developed.  If you have the original portdrvr, the information regarding interfacing that was contained in the zip file applies to this version.  Unfortunately, that version is no longer available here and it must be acquired via other means.