Hi, Cisco supports the "3" database vendors (Microsoft/Sybase, IBM DB2, Oracle) only. So there's no way you get it working with Postgres.
What I would do:
* if it's an UCCX environment:
1. install DB2 Express-C (free of charge) on a separate Linux machine - this is the most cost effective option. Or if you have some money to burn, get a Windows server and install SQL Server Express 2K8 on it. I know it's not Postgres but you have a low cost database integration with UCCX.
2. if 1 is not an option, I'd write a simple PHP/Python/Grails/your-favorite-web-framework application that does basic CRUD on a Postgres database. UCCX scripts can do HTTP GET and POST, after all.
* if it's an UCCE environment:
1. use the Application gateway node from ICM to pull/push data from/to outside.
Have fun exploring,
G.