Hi,
Thanks for the question.
I would recommend configuring XMPP federation with Cisco.com.
Configuration Guide is here;
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/im_presence/interdomain_federation/9_0_1/CUP0_BK_IAAE17D8_00_integration-guide-interdomain-federation-90_chapter_01010.html#CUP0_TK_T17CFBAA_00
Please know that if you see anything for TLS you'll need to skip it. XMPP federation to cisco.com won't do TLS.
Steps are
-Make sure CUPS is enabled for DNS. Run this command from the CLI 'utils network eth0 details' to show what the primary/secondary DNS servers are.
-Enable XMPP on a CUPS node
-Configure an DNS SRV record for the IM domain that points to the CUPS server.
-Make sure that you create an external NAT and open port 5269 on the firewall.
If you get stuck, TAC will always be happy to help you out however this configuration is pretty straight forward. Most issues are related to the SRV record not resolving correctly or the firewall blocking traffic.
Good Luck.
Brad