i've insatlled pgsql + postgis (binary version) in /usr/local/pgsql checking for PQconnectdb in -lpq... no I could not find your PostgreSQL client libraries! Use --with-pgsql-libraries=PATH; if running R's INSTALL, use --configure-args='--with-pgsql-libraries=PATH'; or set PG_LIB_DIR in your environment to the library path, and rerun the configure/install.
how can i install it ?
you'll need to follow the instructions in the block of text above and give the build process appropriate paths for your pgsql libraries. after that, it should just work. [This is not really an R-SIG-Mac specific question, btw.] --e