We want BYU to win all games but if we lose 1 we aren't necessarily in control of our destiny. I've seen blogs that say we're still okay with a loss but I don't think this is true. See below for a tool that you can simulate rest of the season and see who wins tiebreakers.
Most important Non-BYU games
1. Iowa St. v. KState (Final weekend) Cheer for Iowa St. If Iowa St wins this game we are basically still in with a hiccup loss down the stretch
2. Iowa St. v. TTech (this weekend): Cheer for Texas Tech Tech win improves all scenarios and we are likely in because ISU v. KState game becomes an elimination game
3. Colorado @ TTech (2 weeks): Cheer for Texas Tech Basically last chance for Colorado to lose (outside of a major upset).
Here is the tool to simulate the season if you want it:
mred's Big 12 FB Standings Generator