Zipper divisions. Divide the Texahoma 6 between the two divisions with permanent cross-division rivals.
West
Texas------------Oklahoma
Texas Tech------Oklahoma State
Baylor-----------TCU
Kansas----------Kansas State
WVU------------Cincy
UConn-----------Iowa State
I think it would look something like this, but a little different. Two Texas schools per division. Maybe like this with protected crossovers:
West
Iowa State (West Virginia)
Kansas (UConn)
Kansas State (Cincinnati)
Oklahoma (Oklahoma State)
Texas (TCU)
Texas Tech (Baylor)
East
Baylor (Texas Tech)
Cincinnati (Kansas State)
Oklahoma State (Oklahoma)
TCU (Texas)
UConn (Kansas)
West Virginia (Iowa State)
And I know some people will say that OU and UT would be in opposite divisions. But I have seen somewhere (I think Chip Brown) saying they didn't want that to be on the table if the Big 12 went to divisions. So I wouldn't be surprised to see them in the same division.