I've mounted a drive as a folder, mapped a folder as a drive, and mapped one fold on one drive to a different folder on the same drive, but I have not been able to get a folder on one drive to map to a folder on a different drive.
I am running 64-bit Windows 8.
I tried the Junction tool, and the new MKLink command introduced in Windows 7. They don't appear to allow mapping between drives. Wondering if maybe combining a few techniques will produce the desired result.