How many monitors do you have? If you have two, then you can do something like:
If MOUSEX() > SCREEN(1,Right)
Move Mouse to SCREEN(1,MidX),SCREEN(1,MidY)
Else
Move Mouse to SCREEN(2,MidX),SCREEN(2,MidY)
If you have three, you can do the same sort of thing but a bit more of it.
For bonus points, you could check if the mouse is near the center of the screen first and only then move it to the next screen, something like:
If MOUSEX() > SCREEN(1,Right)
If ABS( MOUSEX() - SCREEN(2, MidX) ) < 10 and ABS( MOUSEY() - SCREEN(2, MidY) ) < 10
Move Mouse to SCREEN(1,MidX),SCREEN(2,MidY)
Else
Move Mouse to SCREEN(2,MidX),SCREEN(1,MidY)
Else
If ABS( MOUSEX() - SCREEN(1, MidX) ) < 10 and ABS( MOUSEY() - SCREEN(1, MidY) ) < 10
Move Mouse to SCREEN(2,MidX),SCREEN(2,MidY)
Else
Move Mouse to SCREEN(1,MidX),SCREEN(1,MidY)
So it would move first to the center of the screen it is on, and then on the next call to the center of the other screen.
You might like to add a Highlight Location action to show where it is.