Hi, the only thing I can think of is the plugins configure screen in chankast. Use Port A, Controller, VMS with LCD. This will use windowed output for the screen used by the vmu somewhat the same as a real vmu but without all the buttons. So you can't play any minigames on the vmu screen. The screen isn't visable when fullscreen but only when playing in windowed mode. There's no other program that I'm aware of.
Hope this helps.
ps. If you meant this I should point you to browse all settings of chankast first before posting because the answer is clearly there in the program. That's all.