Yeah, sure, and let's just use lambdas for everything:
(def cons (x y) (fn (f) (f x y)))
(def car (x) (x (fn (a b) a)))
(def cdr (x) (x (fn (a b) b)))
(car (cons 'a nil)) -> a
:P
On a semi-related note, I had an interest a while back for implementing a Lisp interpreter using only lambda-calculus. I'm still not sure if it's possible or not, but I wanted to give it a try.