R/PL cannot build - R/PL without recompiling?

Just changed the list from r-help to this one and hope i am in the  
right place now.
i am trying to get PL / R running on Mac OS X. PostgreSQL is already  
running and connects just smoothly to R via DBI / RPostgreSQL .
I use Mac OS 10.5.7 and PostgreSQL 8.3.7 as well as R 2.9.2

I just read that R / PL does work without recompiling (with enable  
share) on Mac OS X without recompiling and i try to find out how...

so far I put the untared plr to my /Library/Frameworks/R.framework/ 
Resources/
If i just add the path mentioned above to the Makefile and run  
USE_PGXS=1 make :

i get the following error message:

make: pg_config: Command not found
make: *** No targets.  Stop.

If simply run make inside the plr directory i get the following:

Makefile:41: ../../src/Makefile.global: No such file or directory
Makefile:42: /contrib/contrib-global.mk: No such file or directory
make: *** No rule to make target `/contrib/contrib-global.mk'.  Stop.


If I change R_HOME in the makefile to Users/myname (which is supposed  
to be my R home and initial working directory) I get the following  
error message:


*** Cannot build PL/R because libR is not a shared library.
*** You might have to rebuild your R installation.  Refer to
*** the documentation for details.

This is a message i found already on several posts. Some answers  
suggest to recompile R with the shared lib option enabled. Anyway,  
some posts suggests that it is possible without recompiling. I?d  
really like to know how...

Thx in advance for any suggestions !