Unfortunately, not today. The interface provided today is very powerful and you can control just about everything. That also means that you need to control a lot to get the core scenarios working. As we progress in the WiX toolset, we'll build up additional abstraction layers so that a custom BA is easier to write. The Burn functionality is still rather new and just needs time to have more code contributed.
If you want to look on the bright side, be glad that you'll be able to accomplish just about any required UI task because the interface provided is so expressive. :)