[plt-scheme] Interfacing to C on MacOS X

I'm trying to figure out how to link to C code on Mac OS X. When 
I try compiling a module that uses c-lambda and a C file that 
defines that function, everything works fine. But when I try to 
link them using mzc -l, I get the following error:

[dylan:~/Development/scheme/c-test] lambda% mzc -l fact.o fact-
test.o fact-test.kp
MzScheme compiler (mzc) version 201, Copyright (c) 1996-2002 PLT
"/Users/lambda/Development/scheme/c-test/_loader.c":
link-extension:
cc: /Applications/PLT v201/lib/mzdyn.o: No such file or directory

The lib directory doesn't even exist in the PLT directory. Am I 
doing this the wrong way? Or does it not work on Mac OS X? Any 
help would be appreciated.

Thanks,
Brian