I use GAIM. Here's my configuration:
Screen Name: JabberID
Show more options...
Use TLS if available
Force old SSL
Allow plaintext auth over unencrpted streams
Connect Server: mydomain.com
Proxy type: Use Global Proxy Settings
Hope that helps. I can log into Jabber for one of my domains, however I have had trouble logging into a recently transfered domain. This might be DNS related, so if your domain is new or recently transfered, give it some time. Perhaps somebody with more background in this matter can enlighten us.