I haven't looked at stuff as closely as I should, so correct me if I'm wrong, but for OSU fans, you want LSU to win out, 'Bama to lose to Auburn, OSU to win out.
That's the scenario that knocks out Arkansas and Alabama and likely (due to strength of conference) moves Okie State back into #2.
An LSU loss seems to magically help all SEC schools w/o knocking LSU out of the game. Arkansas beating LSU doesn't drop LSU out of the rankings far enough: it merely strengthens the possibility of Arkansas or 'Bama playing LSU in the NC!
As usual, though, too much speculation at this point is nuts. There's football yet to be played. If OSU wins Bedlam, that gives them a late season victory over a high computer ranked team, but ISU could ruin that a little, too, by beating the Sooners first.
Simply put, the best case scenario at this point for OSU is a Bama and Arkansas loss this week.
The very lowest LSU would drop in a loss is (I believe) 4th. It would leave OSU in 3rd, hoping for Alabama or Arkansas (if they win the SEC west tiebreaker) to lose the SEC Championship! If LSU loses and doesn't drop below 3rd and wins the tiebreaker, they go to SEC Championship. If they win, they would play a one loss 'Bama in the NC. If they lose, then 'Bama and Arkansas would rematch for the Least Interesting NC of All Time. Blech.
Caveat: I'm just winging the scenarios here (because there are too many variables, esp. in the case of a 3-way tie), so take all of this with a grain of salt.
But I'm (fairly) confident that, if you are rooting for OSU to have the best shot at a comeback into the NC, you need to root for LSU and Auburn this weekend. (see also: Blech.)