How to fake a drive by using folders

from:
http://www.chami.com/tips/windows/010197W.html

Creating logical drives on the fly

If you have very deep directories (directories with many sub directories inside sub directories), you may find it easier to create a logical drive that points to the directory you want to work in. On the other hand, you may want to simply create aliases to existing drives for those programs looking for a particular drive. Whichever the reason you want to create a logical drive, you can do so using the SUBST command.

For example, to create an alias called D for your C drive, run following command from the "Command Prompt" (or the "DOS Prompt"):

SUBST D: C:\

To create a logical drive called E, that points to your C:\WORK directory:

SUBST E: C:\WORK

To delete the aliases or logical drives that you create using SUBST command, run SUBST with the drive name to delete and the parameter "/D"

SUBST D: /D

SUBST E: /D