Thank you for showing interest in our Visual Studio Extensions!
To my regret the installation of the extensions is too complex - it adds assemblies to the GAC and the Visual Studio folders, registry entries and unpacks files to specific Visual Studio folders.
That's the reason we do not provide a manual installation for them. You have correctly noticed they are currently available only with the Telerik RadControls for ASP.NET AJAX main installer.
the Telerik team