asterisk users - Aug 2007 - Asterisk with IM (instant messaging)

Hi people, I have Asterisk 1.2.13/DebianEtch as my VoIP server, using SIP.

I need to use IM (instant messaging) among X-Lite clients, but when I
send a message to any other client I get the error "Error: method not
allowed". I read Asterisk does not support instant messaging,
so.....What's the best way to have instant messaging with Asterisk ???

Thanks a lot.

Alejandro