You could try handling CurrentCellMoved. In the handler, conditionally set WantsTabKey depending upon whether the current row has tabbing or not.
private void gridControl1_CurrentCellMoved(object sender, GridCurrentCellMovedEventArgs e)
{
if(this.gridControl1.CurrentCell.RowIndex > 1 &&
this.gridControl1.CurrentCell.RowIndex < 4)
{
this.gridControl1.WantTabKey = false;
}
else
{
this.gridControl1.WantTabKey = true;
}
}