Disclaimer: I can't help you with all of the the how-to details on this idea.
Since the save and load processs use a specific series of keystrokes, you should be able to use an AHK script to output a macro of those keystrokes when the save or load button is pressed. Change your "load" and "save" buttons to unused keystrokes so they only trigger the AHK macro.
For example, a macro consisting of "F7", delay __ miliseconds, and "1" loads from slot 1.
If you can't hide the message windows fully, consider putting a very simple message in the window like "Saved" instead of leaving it blank.
Scott