Hi Brandon, actually Pivot formulas are based on values of previous trading period (i.e. week), thus indicator wouldn't need an open.
Do you have the same indicator as me? If yes, then when you watch market during weekend - adjust the number of period to "-1". The point is that in this case it will treat passed week as previous week and will show you the numbers.
But in the begining of the week - return it back to "0". I've found that sometimes it has bug on Mondays - shows pivots incorrectly.
And finally - you can calculate pivots in excell