[plt-scheme] slib under Mac OS X

Hi,
   I wonder if anyone else has had problems getting slib (2d4) working 
with DrScheme under Mac OS X and might have some advice on how to get it 
to work. I'm mostly following the directions in collects/slibinit/doc.txt.
   I've installed slib in the collects directory. I've changed PLT to be 
group writable (sudo chmod 775 PLT). (PLT was formally 755)
   When slib attemts to finish its installation, it gets as far as creating 
slibcat (in the PLT directory) and writing a few lines but bombs out in 
require.scm. PLT says: "read: expected a ')'"
I guess require.scm is trying to use a different read than the one 
provided by PLT. What should I do to fix this?
   Also, I notice that the case forms in require.scm don't account for 
software-type return "macosx". Is the appropriate way to deal with this 
to add macosx to the lists of choices (with UNIX) of these case forms:
((UNIX COHERENT PLAN9 macosx)	'(#\/))
((UNIX COHERENT PLAN9 AMIGA macosx) "/"))))
   I'm using DrScheme v.200 (iteration 0).
   Thank you.

David