There seems to be 2 ways to go. Easiest is to use a library program (like the one MJMP posted the link for) which lets you define your own unit (sysex commands) as one of its modules. So the interface work is done (user interface and midi comms) albeit with their look and feel/widgets (eg sliders/pots/buttons etc). Though this option seems to come with the pay for it pro versions ??
Or we write a PC program (in Visual Basic or Python or C++ etc), where we'd have to write (or purloin (which may decide the prog. language we use)) all the various widgets and user interface and comms (basically write a library program or part thereof).
While there's good information in the ADA midi sysex pdf, I'm not sure it's all there (well maybe for the MP1), but from my quick researching it seems sysex isn't too hard or complicated, just have to get your head around it. I spotted a sysex primer youtube clip (yet to watch) in a google search which is a good start (regardless of which direction we choose).