Are you sure you want to do this? I'm not saying that PostgreSQL has any security issues, but if there are you'll find them quickly given that anyone in the world can now connect to the server process.
Having said that, you don't say what version of PostgreSQL you're running but, by default, the 7.x series and below do not listen on a socket. You must start the postmaster with the "-i" option. I'm sorry but I don't know how to do that through a control panel.
Again, the default for PostgreSQL in 7.x is to not listen to a socket. I'm not familiar with how to do this via a control panel, but you must start the server with the -i option. It will need to be restarted if it is already running.
[list=1][*]That your PostgreSQL is installed in /usr/local/pgsql[*]That your data directory is in /usr/local/pgsql/data[/list=1]
Those are the defaults but neither are required. Basically the directory that the database lives in is specified by the -D option. The -i option tells the dataserver to listen on the default port (5432 as you have already identified).
Also, depending on your system the server traditionally runs as a non-privledged user (i.e. not root).