1. The update won't install:
You must have a full retail version of Return to Castle Wolfenstein installed properly on your system before you will be able to install the update. If for some reason the installer is not able to find your install directory, please see the section below on "Extracting the necessary files without installing."
2. Extracting the necessary files without installing:
Recommended only for System Administrators and advanced users. It is possible to extract the necessary files without running the installer. To do so, simply open the update using any unzip program. Once you have it open, you'll want to replace these original files (located in the RtCW root folder) with the new versions located in the update: