I think pg's On Lisp contains some samples on transforming code to continuation passing style, which would allow us to create ccc. It would also mean bashing the code quite a bit, and CL doesn't necessarily optimize functions that are passed around and called in tail position, unlike Scheme which requires such to be optimize.
Yes, it is not required by the norm, but as far as I know, ACL, SBCL, CMUCL and CLisp all implement tail call optimizations (for the latter, only on compiled functions though). Maybe that could be considered enough to rely on it.
Perhaps I'll have to go back and read that part of On Lisp some time. (I stopped after mvdo because the macros were hurting my head. But perhaps I've developed a thicker skin since then.)
