You can add this line to your start script (instead of the previous non-solution):
JS.eval("$('#txtCommandDiv').css('text-align', 'center')")
That will center the command/input div, which will center the "Continue" message. It will also have the effect of centering the type-in area, which you may or may not want.

If you don't want that, you can always have a function to wrap "wait" where you first set the align to "center" before the wait, and then set it back to "left" after.