I've got Jabberd 1.4 set up so's it stores all the data in a PostgreSQL database; more details on how that's set up is here. But recently I needed to change the connect string so that it connects to a database whose name is different than the user name. Here's how to do that; this is the postgresql element that's a child of the xdb_sql element:

<postgresql>
<conninfo>user=game password=secret dbname=gamedb</conninfo>
</postgresql>

That's dbname, not db or database. This is probably documented somewhere, but hopefully this post will make it easier to Google up...