how can i add some xmlns by client

[lerosua <lerosua@xxxxxxxxx>]

hi.

i want to test something with gtalk. so i hope my client(base gloox) can
perform some feature like follow  by other client get presence.

   <presence from="lerosua@xxxxxxxxxx/iCalk" to="
cycloneblog@xxxxxxxxx/pcp5501FECA" xml:lang="en">
     <priority>
       1
     </priority
     <c node="http://www.google.com/xmpp/client/caps"; ver="1.0.0.93"
ext="sidebar voice-v1" xmlns="http://jabber.org/protocol/caps"/>
 </presence>

so , how can i  add the <c node=".....> to my client.