Question about Rotator

Because of the length of my refractor, to avoid any collisions I'm going to have to limit my rotation on my WR3.5 to between 0 & - 90 degrees.   It's not a big deal, as I can do any other necessary rotation in software.   However, Nina's camera rotation only moves from 0 to 360 degrees, no minus 90 option.   How do I get NINA to know the camera's rotation angle?

Thanks!
Jerry