Components for Delphi and C++ Builder.

type
  TDatesColAreaEhCrack = class(TDatesColAreaEh);

procedure TfrFrameOne.PlannerVertDayslineViewEh1DrawCell(
  PlannerView: TCustomPlannerViewEh; ACol, ARow: Integer; ARect: TRect;
  State: TGridDrawState; CellType: TPlannerViewCellTypeEh; ALocalCol,
  ALocalRow: Integer; ADrawCellArgs: TPlannerViewCellDrawArgsEh;
  var Processed: Boolean);
var
  NewRect: TRect;
  s: String;
begin
  if (CellType = pctDateCellEh) then
  begin
    PlannerView.DefaultDrawPlannerViewCell(ACol, ARow, ARect, State, CellType, ALocalCol, ALocalRow, ADrawCellArgs);

    PlannerView.Canvas.Brush.Color := TDatesColAreaEhCrack(PlannerVertDayslineViewEh1.DatesColArea).GetActualColor;
    NewRect := ARect;
    NewRect.Top := NewRect.Top + 20;
    NewRect.Left := NewRect.Left + 4;
    s := 'New Text';
    PlannerView.Canvas.TextRect(NewRect, s, [tfWordBreak]);
    Processed := True;
  end;
end;

uses
  ...PrintPlannersEh,

type
  TfrFrameOne = class(TMyBaseFrame)
...
  public
    MyPlannerControlPrintService: TPlannerControlPrintServiceEh;
.....
  end;

implementation

uses Unit1, Unit_ToolsDataModule;

{$R *.dfm}

type
  TPlannerViewCrack = class(TCustomPlannerViewEh);

  TMyPlannerControlPrintServiceEh = class(TPlannerControlPrintServiceEh)
  protected
    procedure PrintCellData(ACol, ARow: Integer; ARect: TRect); override;
  end;

procedure TMyPlannerControlPrintServiceEh.PrintCellData(ACol, ARow: Integer; ARect: TRect);
var
  CellType: TPlannerViewCellTypeEh;
  ALocalCol, ALocalRow: Integer;
  Grid: TPlannerViewCrack;
  NewRect: TRect;
  s: String;
begin
  inherited PrintCellData(ACol, ARow, ARect);

  Grid := TPlannerViewCrack(PlannerView);
  Grid.GetCellType(ACol, ARow, CellType, ALocalCol, ALocalRow);

  if (PlannerView is TPlannerVertDayslineViewEh) and
     (CellType = pctDateCellEh)
  then
  begin
    NewRect := ARect;
    NewRect.Top := NewRect.Top + Round(20 * ScaleX);
    NewRect.Left := NewRect.Left + Round(4 * ScaleY);
    s := 'New Text';
    Canvas.TextRect(NewRect, s, [tfWordBreak]);
  end;
end;

....

constructor TfrFrameOne.Create(AOwner: TComponent);
begin
....
  MyPlannerControlPrintService := TMyPlannerControlPrintServiceEh.Create(Self);
end;

....
procedure TfrFrameOne.Button1Click(Sender: TObject);
begin
  MyPlannerControlPrintService.Planner := PlannerControlEh1;
  MyPlannerControlPrintService.Preview;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  FreeAndNil(MyPlannerControlPrintService);
end;