yeah mzscheme is super simple to install on osx. I had similar results to the poster with clisp though. It was the reason I pretty much gave up on common lisp. I could install it and get slime working up on XP no problem, but getting anything to work on osx was difficult. This was a long time ago too and I was running 10.3, so maybe things have changed by now. I haven't tried installing any common lisp system since I've upgraded to 10.5.