There doesn't seem to be much in the way of speaker distance/delay settings except for the center/rear center, pg 43. For each foot of distance difference from the L/R add 1ms of delay. L/R-10ft, Center-9ft, delay=1ms.
Since there's no adjustability for the side surrounds, if possible you'd want to place them the same distance from the listening position as the mains.
Sorry I can't be of more help. This is a relatively older unit with limited capabilities.