Thank you for your interest in our Silverlight suite.
Unfortunately there is no automatic way to register any custom Silverlight control in the current version of Visual Studio. This is a tooling limitation and it will be fixed with VS10.
So currently you need to add the controls manualy in the toolbox - you don't need to add them one by one - just choose the following dlls in order to get all the controls installed in the Toolbox:
Please let us know if you need more info!
the Telerik team