Sevenize and Open Source
Sevenize is built with a new patching engine called Anolis which is a non-commercial open-source application suite and software library written in C# licensed under the GNU Public License (GPL).
The Anolis project is shared by Vize's sister projects: xpize and Vize. The project is managed on CodePlex.
Anolis Packages contain no real 'source code', just a simple XML file that lists the files to be modified. You'll need to use a .NET Resource editor to extract the *.anop package file from the installer, and then 7-Zip to extra the LZMA Tarball package sources.