You can try handling the QueryNextCurrentCell event. If the next cell is off the grid on teh right, explicitly move it to where you want it.
private void gridControl1_QueryNextCurrentCellPosition(object sender, GridQueryNextCurrentCellPositionEventArgs e)
{
if(e.ColIndex > this.gridControl1.ColCount && e.RowIndex < this.gridControl1.RowCount)
{
this.gridControl1.CurrentCell.MoveTo(e.RowIndex + 1, 3);
e.Handled = true;
e.Result = true;
}
}