Mac OS X Lion - How do I turn a "regular" user account into a service account?

During the installation of PostgreSQL using the installer provided by EnterpriseDB, I was given the option to assign a password to the PostgreSQL account. The installer said something about the account becoming "locked" if I don't assign a password. I didn't know what it meant, so I gave a password. Now I know what it was all about: the installer was actually talking about service account vs regular account. Now the PostgreSQL account appears in the login screen and it's an eyesore. What shall I do to turn it back into just a service account and make it disappear from the login screen? I'm guessing it involves using dscl?

A simpler thing to do will be to hide the user from the Login Window. Apple provides a few options on this support article.