We cannot engage with any commitment on the CUIT for Silverlight 5 until it is introduced officially and we evaluate the efforts we need to invest in it. At this point we can only assure you that once there is an official version of Visual Studio with CUIT for Silverlight, we’ll look into it.
Since there is no official statement from Microsoft which is publicly available, we can assume that this feature is tentative and is not 100% possible, I would like to point your attention to our Test Studio
. With TestStudio you can record and playback Silverlight Automated tests.