Adium Instant Messaging
In Adium, under File, choose Add Account and then Jabber as the account type. It will then ask for your Jabber ID and your password. Your Jabber ID is your SIP address, e.g. username@domain.onsip.com and your password is your WWW password.
Next, choose the Options tab. Keep the Connect Server blank, and uncheck Do strict certificate checks.






adium add account instructions
In any case, nothing I have tried so far works.