Here is the answer that no one likes to give: no. There is currently no way in the Silverlight API to invoke the display of the Silverlight configuration dialog.
I would agree that such a function must exist.
Edit
In response to your additional question. In a raised SL4 OOB application, it may be possible to get a shell of scripts to run Silverlight.Configuration.exe. You will find this file at: -
% programfiles% \ Microsoft Silverlight \ 4.0.50401.0 \ Silverlight.Configuration.exe
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