No, you can't change the bots nick with the /nick command., but you CAN change it using 'botnick.tcl' found here on slennox's site. Install it and use .botnick newnick via the partyline. I also wonder how, if still possible, bots could be added to X on Undernet. I know it used to be possible BEFORE X was re-done and users had to register user names. There used to be a .tcl here in the TCL page that would have the bots mesage X, but I presume that would no longer work. Can it still be done?
I'm using services.tcl. But there are some other scripts out to identify a bot to nickserv. Just search for one you like in the scripts section on this site or in some of the script archives on the net.