I think UT, MSU and Vandy are the only locks. Arkansas, Ole Miss (yes, Ole Miss), Florida and Kentucky are fighting for at large spots. I don't think there is a certain number of spots slotted for the SEC, but I would bet it will be at least 4 and no more than 6.
Projected minimum needed to get in:
Arkansas: 1-1 (at UM, AU)
UM: 2-0 (Ark, at UGA) + 2 in Atlanta (likely UGA and UK)
Florida: 2-0 (UT, at UK) + 2 in Atlanta (likely AU and MSU)
Kentucky: 1-1 (at USC, UF) + 1 in Atlanta (likely UM)
If all the regular season stuff plays out, the UK/UM SEC tournament game may be the elimination game.