EDIT: First off, a lot of people are saying Michigan only needs to be in the top 18, but this is incorrect:
"if fewer than 10 teams are eligible for selection, then the Bowls can select as an at-large team any Football Bowl Subdivision team that is bowl-eligible, has won at least nine regular-season games and is among the top 18 teams in the final BCS Standings subject to the two-team limit noted above and also subject to the following: (1) if any conference has two or more teams in the top 14, then two of those teams must be selected and (2) from the teams ranked 15-18, a bowl can select only a team from a conference that has fewer than two teams in the top 14"
By this rule, a Big 12 team gets chosen first.
So, Michigan needs to be in the top 14, end of story.
LSU over Georgia
Southern Miss over Houston (houston will, most likely, drop below michigan if this happens.. It will also free up another BCS at large spot, so Michigan would still get an at large bid with a georgia win)
If both of these happen, Michigan is all but guaranteed in the BCS. If neither happens, michigan is 100% out.
IF only one happens, and Baylor jumps Michigan (which is a definite possibility if they beat Texas), Michigan will need more help to move from 15th to 14th in the form of:
- Ok state over Oklahoma
- Iowa State over Kansas State
- UCLA over Oregon
- New Mexico over Boise
(also, Michigan jumping the B1G championship loser is a near-certainty, so i'm not too worried about the margin of victory in that game)
A Simplified (and only realistic) Rooting guide is:
and one of:
- Texas over Baylor
- Oklahoma State over Oklahoma