rjmurdock,
You can use JustMacros with the OnPreviewChange event to do almost what you want:
What you need to do is, create an script that performs a Transition, but records the time the transition started, so that you can ignore the Preview Change event that fires at the end of the transition.
So your event might look something like this:
You can ensure the event starts whenever you start the application by adding to you autoexec the line:
You will then be able to use the BMD Switcher Application, but whenever you select a preview source, it'll transition.
You can turn it on and off by executing this script.
You might need to zoom in to read the text, but it's really quite simple, and I just tested it and it works fine. If you would like the script in Text form, you can access it here, but remember to break it up into 2 scripts and one line added to the AUTOEXEC.
http://www.justmacros.tv/scripts/HotTransitions.LuaScript.txtBest Wishes and good Luck with your project.
John