One way is to pass the size and position as parameters to the DLL function, so when the DLL front panel lunches it changes the size and position. Also create another function (VI) in the DLL that accepts the size and position as parameters and adjust the window accordingly.
Another possible way is to get a windows handle to the panel (WinAPI - FindWindowA) and then change the size and positions. I am not familiar with MFC so I am not exactly sure how to accomplish this. Joe