There is no way to use SAML authentication for accessing SMA.
What we have been doing is moving SMA functionality into the standard Pega Platform. Admin Studio will replace SMA starting in Pega Infinity (Pega 8.1). You would use the same SAML configuration to access Admin Studio that end user would use to access the application.
Also, in 7.2.2 to 7.4 there is a System -> Operatation landing page that has a lot of functionality of SMA. The higher the version the more functionality you will see there.