Peter Norvig has a simple Scheme interpreter (tail recursive, with call/cc) implemented in Common Lisp at http://norvig.com/paip/README.html - it would probably be a reasonable basis. One option would be to implement Scheme in Common Lisp, and then simply run the existing Arc ac.scm on top of that. But it would probably make more sense to cut out the middle layer and modify Norvig's code to run Arc instead of Scheme.
