If SASL is on, how to set the client params?
Which parameters? GSSAPI? Most of the time you will just have a tuple of username and password.
And BTW, will the XMPP Server do sth. in order to enable SASL Authentication?
SASL Authenticate is required by the current XMPP RFC(s) 6120. I don't know a up-to-date XMPP server that doesn't at lest support SASL DIGEST-MD5.