If your provider gives you a dynamic IP address, you can use the popular "ddclient" to update your tunnel configuration (see http://www.tunnelbroker.net/forums/index.php?topic=1994.0
Ubuntu user can use apt to install the package:
sudo apt-get install ddclient
Other linux user may use their package tool or download the package from http://dyn.com/support/clients/linux
Example configuration /etc/ddclient.conf
protocol=noip,server=ipv4.tunnelbroker.net 12345 username password
Replace 12345 with your tunnel ID, username and password with your registered account. This configuration runs the ddclient in background and check for an IP update any 5 minutes. To detect the IP the client uses a web page (located at dyn.com). If it finds an IP change, it opens the tunnelbroker.net update page and set the new client IPv4.