Thank you so much, that helped.   
What I was tripping over was page 38's assertion that EXEC had a mini-layer or dynamic key mapping capabilities.  The example they gave seemed to indicate that you could code on the fly state sampled key layering.  I read this to mean an alternative to IOUMD.  In essence, that any switch "state" could be used, surgically, as a layer.   
This is the example they gave...I just tried to adapt it, unsuccessfully   
 MapKey(&Throttle, APPAT, EXEC("MapKey(&Throttle, APENG, L_ALT+'6');"));
MapKey(&Throttle, APAH, EXEC("MapKey(&Throttle, APENG, L_ALT+'2');"));
MapKey(&Throttle, APALT, EXEC("MapKey(&Throttle, APENG, L_ALT+'4');"));    
Anyway, I'm using Aussiedroids outstanding Elite Dangerous target script which already had shifts setup, so i just added   
 //David Start 
MapKeyUMD(&Joystick,H4U,
                          DX15,                    //UP Layer
                          DX15,                    //MIDDLE Layer
                          DX28             //DOWN Layer
                           );
MapKeyUMD(&Joystick,H4D,
                          DX17,                    //UP Layer
                          DX17,                    //MIDDLE Layer
                          DX30             //DOWN Layer
                           );
                           
//David Stop    
Works GREAT, THANK YOU!