First of, you may want to have a look at our Visualizers documentation, if you haven’t already.
However, you can always write your own visualization handlers from scratch. You don’t have to use the provided base classes, although they simplify the process somewhat.
The “Custom” mode that you can select on the visualizers you write, requires you to override the “GetContextsToVisualize” method in the visualizer. In that method, you must populate the provided list of contexts “contextsBuffer”, even if there is just one. Thus, you must provide your own method for getting ahold of the correct Context object(s).