(1) The winner of the SEC Title game goes to a BCS Game, which is the Sugar Bowl unless they qualify for the BCS Title Game.
(2) A 6-6 team cannot get an SEC Bowl tie-in selection that would leave an SEC team with a winning record home without a bowl game.
(3) A team cannot get an SEC bowl tie-in selection that would leave an SEC team with a two game better record at home without a bowl game. This rules doesn't matter much in actuality, because the only scenario that would apply is that a 7-5 SEC team can't go to a bowl game and leave a 9-3 team at home. With all the bowl tie-ins now, this just isn't feasible.
That's really the only three hard and fast rules. But the SEC Bowl selection process is a complete horse-trading negotiation between all the bowl games, the SEC Office, and the individual schools. The SEC has a couple of other general rules they TEND to go by, but there's nothing in writing that this must be so. The first tendency is that the loser of the SEC Championship Game will never drop below the Cotton or the Outback Bowl. The other tendency is that a team with a 2 game better overall record don't get jumped in the "tier" by a team they're 2 games in front of. For example, MSU likely wouldn't get jumped by a 6-6 Georgia or a 6-6 Tennessee into the Cotton/Outback/Peach (3/4/5) tier, but we could get jumped by Florida. But in that scenario, the Gator is as far as we should drop, because the Gator gets the SEC #6 tie-in and shouldn't be able to pass on us for a 6-6 team. But there's nothing that mandates it. It's all a horse-trading exercise.
BFB