plays in the conference championship: UH and KU. Why?

First Tie-Breaker Rule:

If all teams involved in the tie did not play each other, but one team defeated all other teams involved in the tie, the team that defeated all other teams in the tie is removed from the tiebreaker, and the remaining teams revert to the beginning of the applicable tiebreaker process (i.e., two team or three or more team tie).

Between BYU/KSU/ISU...only KSU plays the other two teams and they obviously lost to BYU. They still need to play ISU. If they lose...they're out. If they beat ISU...we move on to the next tie-breaker.

Second Tie-Breaker Rule:

The records of the three (or more) tied teams will be compared based on winning percentage against all common conference opponents played by all other teams involved in the tie.

Only two teams have played (or will play) all three of BYU/KSU/ISU:  UH and KU.  That's 6 games.  BYU and KSU still have their two games against those two schools. ISU is 1-0 (beat UH).  

There's more options that I just didn't want to bother typing in.  What is important for BYU:  1st - Win all games.  2nd - Beat UH and KU. 3rd - Beat the highest conference finishers on your schedule.  As it stands today (based on importance of the game and the other team's current standings): Beat ASU (2-2) and then the rest are currently 1-3 so who knows how they'll finish.