Hi there,
       The sources (modified from Alex's version 8 source) are available in the downloads section, under seti@Home modified source section.  I appreciate that doesn't document the process of how the port was accomplished, but can say:
           - Many small changes to fundamental data types were required to convert to Windows from Mac Code
           - A few key library functions had to be researched for suitable alternatives and changed to different vendor libraries
           - A small bug, that caused no problems on Macs, but Crashed Windows version was found and fixed.
          - Extensive exploration if Alex's intended functionality had to be explored, and tried several combinations of settings and optimisation techniques, and incorporated ones learnt form Lunatics development also.
          - A new dedicated profile guided optimisation regime was developed and refined
          -Windows builds were extensively tested, compared, refined and selectively promoted to release.

I hope that gives some idea,  the real process, of course, spans quite a while and with several main contributors.

Jason