The scroller appears in whatever module position you specify when you set it up. The name of the div for the module position is determined by the theme you are using. There is no way for us to tell you how to center the module position, but I can tell you that the div ID for the scroller itself is VMJScroller.
You will have to use css to position that div within the module position as you need it. Otherwise, choose a module position from your theme that is already positioned where you want it.
Jerry