[NumLock]

Код:

uses
  MSHTML,

type
  TForm1 = class(TForm)
    WebBrowser1: TWebBrowser;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);

procedure TForm1.Button1Click(Sender: TObject);
var
  i: Integer;
  elem: IHTMLElement;
  document: IHTMLDocument2;
  all: IHTMLElementCollection;
begin
  WebBrowser1.Navigate('ya.ru');
  while WebBrowser1.ReadyState<READYSTATE_COMPLETE do 
    Application.ProcessMessages;
  document:=WebBrowser1.Document as IHTMLDocument2;
  all:=document.all;
  for i:=0 to all.length-1 do
  begin
    elem:=all.item(i, '') as IHTMLElement;
    if elem.tagName='INPUT' then elem.innerText:='hello world';
  end;
end;

http://data.cod.ru/128530