You can set the value of a single cell, but you cannot ''set'' arbitrary style properties on a single cell. The reason is that the only thing stored on a cell by cell basis is the cell value (which is stored in the underlying data).
If you want to change a cell style on a cell by cell basis, then you have to use the QueryCellStyleInfo event. Here is some code that makes record cells in the first column red and readonly.
private void gridGroupingControl1_QueryCellStyleInfo(object sender, GridTableCellStyleInfoEventArgs e)
{
GridTableCellStyleInfo style = (GridTableCellStyleInfo) e.Style;
if (style.TableCellIdentity.TableCellType == GridTableCellType.RecordFieldCell
|| style.TableCellIdentity.TableCellType == GridTableCellType.AlternateRecordFieldCell)
{
GridColumnDescriptor column = style.TableCellIdentity.Column;
if (column.TableDescriptor.Columns.IndexOf(column) == 0)
{
e.Style.BackColor = Color.Red;
e.Style.ReadOnly = true;
}
}
}