I have added following entries in the kamailio configuration file. I am only mentioning the xmpp section.

"
####### Global Parameters #########

alias=sip-xmpp.kevin.org

####### Modules Section ########
#!ifdef WITH_MYSQL
loadmodule "db_mysql.so"
#!endif

loadmodule "mi_fifo.so"
loadmodule "kex.so"
loadmodule "corex.so"
loadmodule "tm.so"
loadmodule "tmx.so"
loadmodule "sl.so"
loadmodule "rr.so"
loadmodule "pv.so"
loadmodule "maxfwd.so"
loadmodule "usrloc.so"
loadmodule "registrar.so"
loadmodule "textops.so"
loadmodule "siputils.so"
loadmodule "xlog.so"
loadmodule "sanity.so"
loadmodule "ctl.so"
loadmodule "cfg_rpc.so"
loadmodule "mi_rpc.so"
loadmodule "acc.so"

# XMPP
loadmodule "xmpp.so"

# ----------------- setting module-specific parameters ---------------

modparam("mi_fifo", "fifo_name", "/var/run/kamailio/kamailio_fifo")

modparam("rr", "enable_full_lr", 1)

# XMPP
modparam("xmpp", "domain_separator", "*")
modparam("xmpp", "gateway_domain", "sip-xmpp.kevin.org")
modparam("xmpp", "xmpp_domain", "xmpp-sip.kevin.org")
modparam("xmpp", "xmpp_host", "xmpp.kevin.org")



###############XMPP
# initial sanity checks -- messages with
        # max_forwards==0, or excessively long requests
        if (!mf_process_maxfwd_header("10")) {
                sl_send_reply("483","Too Many Hops");
                exit;
        };

        if (msg:len >=  2048 ) {
                sl_send_reply("513", "Message too big");
                exit;
        };

        ### absorb retransmissions ###
        if (!t_newtran()) {
                sl_reply_error();
                return;
        }
        if (method == "MESSAGE") {
                log("*** xmpp-handled MESSAGE message.\n");
                if (xmpp_send_message()) {
                        t_reply("200", "Accepted");
                } else {
                        t_reply("404", "Not found");
                }
                return;
        }

        log("*** xmpp: unhandled message type\n");
        t_reply("503", "Service unavailable");
        return;
###############

"