To make the installation of ExtraLINQ easier, I have created a NuGet package called ExtraLINQ and submitted it to the official NuGet feed (see NuGet » Packages » ExtraLINQ). You can use both the Library Package Manager and the Package Manager Console to install the package.
Using the Library Package Manager
To install the package using the Library Package Manager, right click on References, hit Manage NuGet Packages... and select Online in the navigation panel on the left side. Select the search box in the upper right corner, type in
extralinq, hit enter. Finally, click the Install button on the listed package.
Using the Package Manager Console
To install the package using the Package Manager Console, select View, expand Other Windows and select Package Manager Console. Type in
install-package extralinq. Make sure that Default project is set to the correct project within your solution.