Thanks to this blog post I got it running, though I was not less than five hours hunting. Gee, I wish there was a tool which would let me find the shortcuts to the solution of any problem :-).
After we had followed all the install guides and double and triple checked everything those were the tweaks we needed to do to get it really running:
Edit OpenFire properties - Log into OpenFire as an administrator and add two server properties:
xmpp.httpbind.client.requests.polling = 0
xmpp.httpbind.client.requests.wait = 10
These are required because of a bug where JWChat won’t respect the polling values given to it by the server.
happy chatting away …