cable help

Hi everyone, I have an off-line knitalong friend, who is using 3 of the 6 stitches in the middle cable to make an opposite colored stripe of cable. His predicament is that the opposite color on the backside is very sloppy and haphazard looking. Does anyone know if there is a way to remedy this? is there a way to carry the predominant color over the three stitches neatly?? Thanks!!!