Estoy intentando instalar rpy2 para Python3 con el siguiente comando:

easy_install-3.2 rpy2

Esto da algunas advertencias y un error:

warning: no previously-included files matching '*patch*' found anywhere in distribution
warning: no previously-included files matching '*diff*' found anywhere in distribution
warning: no previously-included files matching '.hg' found anywhere in distribution
no previously-included directories found matching 'dist'
gcc-4.2 not found, using clang instead
Compiling with an SDK that doesn't seem to exist: /Developer/SDKs/MacOSX10.6.sdk
Please check your Xcode installation
build/python3_rpy/rpy/rinterface/_rinterface.c:51:10: fatal error: 'signal.h' file not found
#include <signal.h>
         ^
1 error generated.
error: Setup script exited with error: command 'clang' failed with exit status 1

El archivo/Developer/SDKs/MacOSX10.6.sdk Parece que falta, aunque tengo instalado xcode 4.5.1.

No hay ningún archivo llamadoMacOSX10.6.sdk en "Descargas para desarrolladores de Apple" en la página de inicio de Apple. ¿Qué debo hacer?

PD. Todo funciona bien si no especifico python3.