After some careful thought and a lot of tedious work by developers Brenton and Corey (mental core), you can find a Maya Render Settings UI for testing. Barton Gawboy is project management. The purpose of this UI is to provide a more official/intended workflow for mental ray. This also means makers of UIs for other packages can use this as a template for features on modern mental ray (3.10 and future).
This UI is in an early phase and should not be used for production. Currently the Quality settings have been re-worked to provide a simpler interface and a modern workflow for using mental ray in Maya. Over time we will be improving on this (light and passes tabs to be re-worked) and adding documentation. We recommend Maya 2013 SP1.
You can find the scripts on the Google Code page: Maya Render Settings UI
A further discussion can be found on the ARC forum (must be a member): Maya Options UI