installing laser scanner on Turtlebot 2 for SLAM

edit

I would like to install a Hokuyo UTM-30LX-EW laser scanner on a Turtlebot 2 and try the SLAM demo (http://www.ros.org/wiki/turtlebot_navigation/Tutorials/Build%20a%20map%20with%20SLAM). I managed to make the sensor work with the urg_node driver (https://github.com/ros-drivers/urg_node) in groovy, but in RVIZ it is always missing the /laser frame. I suspect I need to configure TF, but I don't know how, I can't add a new node to TF in RVIZ. Can anybody help, what and how should be adjusted in order to make the laser scanner work in the SLAM demo?