Unless you write a script (php, perl, etc) that connects to the server, joins ur channel, does a names lisitng and counts the users, and disconnected every time auser visits the page--its wont happen. The only other alternative is you, yourself, run a timer that sends a query to a page updating user count. Such as php could do:
www.somepage.com/users.php?count=<number>And use sockets to connect and update the webpage via users.php
