Open "Control Panel -> System" and click on the "Advanced Tab" and then the "Environment Variables" button:
Then under "User variables for ...,", click the "New" button and enter the Variable Name and the paths you want Ansys to search. Paths are separated by semicolons. I have Ansys first search my working folder called "c:\ansys\dee" (use whatever folder you want for this). Then specify the location of the folder where the tool library is located. This folder must match the one defined in the shell script "getmacs". The getmacs script is located at http://btdt.org/prog/ansys/apdl/getmacs and should be saved in the "c:\cygwin\usr\local\bin" folder.
Click the "OK" button
NOTE: Use forward-slashes "/" instead of back-slashes "\" here.
Click on the three "OK" buttons and exit Control Panel. The next time you start Ansys, it will pick up the location of the tools and the new path variable.