OK scrub that LOL, just tried via a macro and it doesnt work for some reason. You will need to do it via a screen button. You can make the button invisible and place it somewhere on the screen you wouldnt normally press.
To do that open the screenset in Screen 4 and choose the Image Button Icon, click once on the screen so that the button appears and then click the None Icon so you dont end up putting buttons at every click

Next double click on the new button and choose it to be a VB button and then OK. Place the button where you want it then exit screen 4 and start Mach, go to Operator menu and choose Edit Button Scripts and then click where you placed the button (you wont see it because you never assigned an image

) The editor should open, just put
DoOemButton(349) in the button and then save and exit.
On General Config page choose the option to hide system menus then restart Mach. Menus should be gone but if you click on the invisible button they should re-appear.
Hood