The original source code for the snippets can be found on the MSDN Code Gallery.
Update: version 1.1 now supports Visual Studio 2013.
With this extension, these snippets will be available through the IntelliSense technology inside the code editor, so that you will not need to use text editors and lots of copy-paste operations. Also, with IntelliSense you can take advantage of additional information and of the so-called replacements.
Remember: the author of this extension is not the author of the code snippets, which have been kindly offered for free by the LightSwitch Team. See the MSDN Code Gallery link above for further information.