VSTabs uses WTL to manage all its windows so before building, download WTL, extract the files and add the extracted include directory to the list of include directories in Visual Studio using the "Tools > Options > Projects > VC++ Directories > Show directories for > Include Files" dialog.
The solution contains a project called VSTabsTest that can be used to check changes to the tab control without running Visual Studio.
VSTabsSetup is built using Windows Installer in XML. To build VSTabsSetup, download WiX and extract all the files to "C:\Program Files\Windows Installer XML\bin" (or change build.cmd to look for the tools in another location). VSTabsSetup is designed to work only with release builds.