How to use file-based config for Saml2SecurityTokenHandler?

Question

Using Saml2SecurityTokenHandler to validate SAML2 bearer token from internal provider or from ACS. Able to programmatically configure the handler to validate just fine, but it doesn't seem to want to pick up configuration from the microsoft.IdentityModel section in my config file. Constructing a SecurityTokenHandlerCollectionManager seems to have no notion of the named configuration section either so I can't seem to use mySaml2SecurityTokenHandler .Configuration - mySecurityTokenHandlerCollectionManager["NAME"].Configuration.

Is there a good sample of setting this up somewhere?