[NumLock]

так:

Код:

type
  TZzzComponent = class(TComponent)
  private
    FParam: string;
  public
    property Param: string read FParam;
    constructor Create(AOwner: TComponent; const AParam: string); reintroduce;
  end;
...
{ TZzzComponent }

constructor TZzzComponent.Create(AOwner: TComponent; const AParam: string);
begin
  inherited Create(AOwner);
  FParam:=AParam;
end;

использование:

Код:

TZzzComponent.Create(Self, 'hello world');