mysql/posgresql pooling

Hi, I run a servlet that runs on a Resin 3.0.2-webserver with MySQL and
PostgreSQL database server.
Operating system is Red Hat Enterprise Linux ES release 3 (Taroon Update 4).
Resin uses its own pooling mechanism. I can make normal connections through
both MySQL and PostgreSQL. However, when I try to get a connection from a
pool, only MySQL connections are returned. How do I tell my servlet it needs
a PostgreSQL connection instead of MySQL?

Kind regards,
Nico.