How to run recurring tasks on Postgresql without an external cron-like tool?

I would like to call a stored procedure on a regular basis. On Oracle, I would create a job for this. I have found that Postgresql can mimic this well by using an external tool (cron etc) and PgAgent. Do you know of an "internal" alternative which wouldn't involve the external tool ? - I want to avoid security concerns with the password stored on the command line of the pgAgent. - I want to avoid any additional system configuration for hiding the password (~/.pgpass). **Postgresql 8.3**
**Linux RedHat 64bit**