As the (current) author of POE::Component::Jabber, I highly suggest you /not/ use XML::Stream. PoCo::Jabber::Client::XMPP will automatically handle all of the various layers of negotiation for you (including TLS). All you have to do is provide a input event and you are on your way to manipulating an active stream. There are even examples in the distro of using the various client classes.
NPEREZ