Create in your psyBNC home following file:

./psybnc/scripts/
Name: USERnn.SCRIPT
"nn" set the personal account number.

Paste the code in the file.

--

CODE
;X-auth and mode +x (hidden host) on irc.undernet.org
server 004 *!*@* * * echo ":$USERNICK PRIVMSG X@channels.undernet.org :login USERNAME PASSWORD" >&1
server 004 *!*@* * * echo "MODE $USERNICK +x" >&1

--

<USERNAME> replace it with your X-Username.
<PASSWORD> replace it with your X-password.
Skip the 2nd line, if you do not want the hidden USERNAME.users.undernet.org host

Afterwards make a /SRELOAD on the psyBNC to install and activate the script.

Afterwards make a /SRELOAD on the psyBNC to install and activate the script.