Thank you for your post, and I apologize for the late reply.
Only FileMaker Server 9 cannot be installed to something other than the C: drive (or whichever drive the OS is installed). The was changed in FileMaker Server 10 so you could install to any drive.
What if you install to the C drive, then move the folder to the D drive.
Go into the registry and change all the settings for the filemaker services to the right drive, and find any other settings and change them. Bet you could make it work.