There is no such animal from Uniden for the XT scanners. However, FreeScan is a very well supported freeware package that will handle the 996XT. The user's guide for this software is here
If you are totally new to this world, I would read up on some of the links that are shown in the wiki homepage. Just go to the blue toolbar under the Scanner Master ad, float your mouse over Wiki and click on Wiki Homepage. Reading up on Trunking Basics in the newcomer's area, and the first couple of topics - defining what DMA is, and how systems, sites and groups relate to one another - in the Uniden DMA FAQ (in the popular topics area) will get you started.
It should be pointed out that there are several features on the XT model that the original T model doesn't have; however if you understand the older T model as described in the Easier to Read guide, it's a short logical jump to the XT. 73 Mike