The precident has already been set: Nebraska and Oklahoma (2001 and 2003, I believe) both played in the title game without winning the Big 12. So, if they can let a Big 12 team be in it without winning their conference, they can let an SEC team be in it without winning theirs.
I would probably support a rule change to make it so that in conferences with a championship game, if two teams tie with the same record in the division, BCS rank rather than head-to-head results is used to determine who goes to the championship game. In other words, the SEC championship game would always feature the highest ranked team from the west against the highest ranked team from the east.