1.) Navigate to %localappdata% (or run %appdata% on Windows XP, or look under C:/Users/YourName/Appdata for Windows 8)
2.) Here, you will find the com.readcube.desktop folder.
1.) Go to ~/Library/Preferences and look for the folder com.readcube.desktop. If you can't find this fold here, check under ~/Library/Application Support.
2.) Here, you should find the com.readcube.desktop folder.
If all else fails, perform a search on your computer for a com.readcube.desktop folder and you should be able to find it. The actual .exe file that will run your ReadCube program is located in the "application" subfolder, feel free to drag it to your desktop to create a shortcut.