I've been looking backwards, d: \ home to c: \ home, and it's easy you just have to copy the folder D:\HOME to C:, modify the CONFIG.SYS and the two lines of home D: to C:
SET HOME = D: \ HOME \ DEFAULT
SET MOZILLA_HOME = D: \ HOME \ DEFAULT
And it is running, but not backwards.
What else would have to edit files? for c:\ to d:\
Saludos