The cellolin can be heard during the "Leaf" solo on Believe, although significant improvements have been made in the tone due to better electronics since that recording. The body and bottom of the neck are cedar, and the rest of the hardware is maple. There's a homemade lever-type metal fine-tuning system at the end of the neck, and the tuning pegs are located near the shoulder (2-up, 2-down). There is a truss rod which extends the lenth of the instrument - clear through the body and down to the end of the neck.
Update 2008: The cellolin has gotten some more use recently! It appears on both the 'Air' soundtrack and 'Resistor' album. It's often playing along with lots of other strings and is a little hard to pick out of the mix - but you can especially hear it near the end of the crazy instrumental section of Resistor's "Restless Angel." It's that wonderfully heavy last "daaah, da-da-da-da, daaah, da-da-da-da" bit.