This article describes how to install Telerik UI for Silverlight manually from a ZIP file.
Open the UI for Silverlight download page following the instructions in the Download Product Files article.
Download the ZIP file and extract it in the desired location. This will give you the UI for Silverlight dlls along with some additional files.
When you download and unzip the archive you will get the following folders.
Binaries: Contains the XAML version of the Telerik dlls.
Binaries.NoXaml: Contains the the NoXaml verison of the Telerik dlls.
Read more about this in the Xaml vs. NoXaml article.
LicenseAgreements: Contains the UI for Silverlight EULA, and the license agreements of any third party libraries used by UI for Silverlight.
Themes.Implicit: Contains .xaml resource files (ResourceDictionaries) holding all the styles and templates of the Telerik controls.
The manual installing using the files from the .ZIP is actually simply referencing the Telerik dlls in a Silverlight Visual Studio project. You can follow the instructions on the topic in MSDN and reference the Telerik assemblies.