[NumLock]

да, возможно, если классы находятся в одном модуле (unit):

Код:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TMyForm = class
  private
    FBla: Integer;
    procedure Sleep;
  end;

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
    FMyForm: TMyForm;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{ TMyForm }

procedure TMyForm.Sleep;
begin
  Windows.Sleep(FBla);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  FMyForm:=TMyForm.Create;
  FMyForm.FBla:=5000;
  FMyForm.Sleep;
  FMyForm.Free;
end;

end.