ITest = interface(IDispatch)
    ['{B3C48C9D-3DF7-489F-9D20-D321D36392A8}']
    procedure Method1(p1: Integer; p2: Integer; p3: Integer); safecall;
  end;

var O : IDispatch;
begin
  O := CreateOleObject('Project1.Test');
  (O as ITest).Method1( 1 , 2 , 3 );
end;

var O : IDispatch;
  Disp: TDispParams;
  Args: array[ 0 .. 2 ] of TVariantArg;
begin
  O := CreateOleObject('Project1.Test');

  // Присваиваю аргументы
  OleVariant(Args[ 0 ]) :=  1 ;
  OleVariant(Args[ 1 ]) :=  2 ;
  OleVariant(Args[ 2 ]) :=  3 ;

  with Disp do begin
    rgvarg := @Args;
    cArgs :=  3 ;
    rgdispidNamedArgs := nil;
    cNamedArgs :=  0 ;
  end;

  O.Invoke( 1 ,GUID_NULL,GetThreadLocale,DISPATCH_METHOD,Disp,nil,nil,nil);
end;