How to run 2+ versions of PostgreSQL concurrently

I'm looking forward to installing 7.4 on my computer, and I'd like to
do so without displacing my current 7.3.2 installation. I've been
looking through the documention as to how to do this, and would like to
hear some feedback on my plan before I implement it.

I'm sure others already do something like this, and that there's
probably information about how to do this out there. If you'd point me
in the right direction, I'll gladly follow the link.

7.3.2 is currently installed in /usr/local/pgsql (the default
location). I'd like to install 7.4 in a directory on a different volume
that I've made a symlink to, accessible from /usr/local/pgsql2.

During configuration, I need to set the directory and port (besides
other, unrelated flags), using
--prefix=/usr/local/pgsql2 --with-pgport=5433

When initializing the database cluster, I need to create an
environmental variable (such as PGDATA2) set to the directory where the
data will be stored.

One thing I'm concerned about is psql and other shell commands. I'm
assuming things have (or could possibly have) changed between 7.3.2 and
7.4 and I need to make sure the each psql works with its corresponding
database cluster. I'm also wondering how I differentiate between the
two postmasters.

Thanks in advance for any advice or pointers!

Michael