Install R on Snow Leopard from source

tar zxvf R-devel.tar.gz
cd R-devel

tools/rsync-recommended
./configure --with-blas='-framework vecLib' --with-lapack --with-aqua --enable-R-framework CC='gcc -arch x86_64'  F77="gfortran -arch x86_64"
make

sudo make install

HT Sequence Analysis with R and Bioconductor

http://manuals.bioinformatics.ucr.edu/home/ht-seq