This is still of alpha quality and missing most of the features of the XSL Proposal! I am working on perfecting the core of the processor, then I'll move on to adding most of the needed functionality and documentation. As it currently works, the only pattern that works is target-element, all flow objects are just massaged(lower-case attributes applied via style, rest applied directly) and passed through, and only children work inside the action. See the source for more info.
For now, enter some XML and XSL and hit process, then you'll see an alert box showing the HTML, and then a window displaying it.