Check the makefile for the postgres 2.0 driver. Look at the PGLIB enviroment variable. Then set it to your pgsql/lib directory. /usr/local/pgsql/lib should be the default and it should work. Then do a make, make install. If that doesn't work, post the error messages.
You will also need to run "createuser nsadmin" as the postgres user. Answer yes to both questions. Then login as the nsadmin user and run "created openacs-4". Start aolserver and you should be good to go.
