why are you trying to do this via a postgresql trigger as opposed to using a service contract via the tcl api (which notifications was designed to do)? Take a look at the way forums integrates with notifications - that is how it is "supposed" to be done. If you have a very compelling reason to do this via a trigger then you probably want ot use NEW.field1, NEW.field2 as placeholders in your proc to submit that info to notifications.... do a grep through packages like this for an example...
/web/service/packages/# grep -R "NEW." * | grep "/postgres"
