[Setup]
AppName=My Program
AppVersion=1.5
PrivilegesRequired=lowest
DefaultDirName={pf}\My Program

[Code]
var
  MyPage: TInputFileWizardPage;

procedure InitializeWizard;
begin
  MyPage := CreateInputFilePage(wpWelcome, 'Caption', 'Description', 'SubCaption');
end;

procedure CurPageChanged(CurPageID: Integer);
begin
  if CurPageID = MyPage.ID then
  begin
    MyPage.Caption := 'New caption';
    MyPage.Description := 'New description';
  end;
end;