triggers/functions across databases

We are migrating from Informix to Postgres 7.4.7 and are having a
difficult time finding if postgres can insert/update tables across
different databases. Namely using functions/triggers when an
update/insert is performed on a table it updates/inserts in a table on a
different database. Informix can do this with no problem but we were
wondering if there is an easy way for postgres to do this. I've searched
numerous sites and found vague answers. Thanks in advance.

Eric Jones