Profiling lisp with SBCL and Mac OS X

I just posted some code for profiling with shark (part of the CHUD toolkit on Mac OS X) and SBCL. I've been writing some fancy n-body integrators using common lisp for a research project, and wanted to profile the code. SBCL comes with a profiler (sb-sprof), but it doesn't work well---at all---on Mac OS X (see the reply to this message of mine for a description of the problem). So, I cooked up this code (with some help from Juho Snellman) which lets me use shark for profiling. It's quite a hack, but it does the job.