You don't need cons, car, cdr, etc. They can all be implemented using lambda. For example:

  ;; excuse my possibly hybrid notation
  (defun cons (car cdr)
    (lambda (m)
      (if (eq? m 'car) car
          (if (eq? m 'cdr) cdr
              nil))))
  (defun car (obj) (obj 'car))
  (defun cdr (obj) (obj 'cdr))