After you install this program, DO NOT RUN IT until the cracked file is added:
Copy mdm.dat to /Applications/Rosetta Stone Version 3.app/Contents/Resources, and make sure to REPLACE the existing file.
(You can do this in the Finder by right-clicking on the Rosetta Stone Version 3 application and selecting "Show Package Contents", and going to the Contents and then the Resources folder.)
Also, make sure you don't update or register if it asks you to.