There are several companies apparently that come under the Tchou Tchou Train Banner, some are exclusive to the Cruise Ship Companies, others are private operators that you can book independently from the Cruise Ship Terminal.
As I rarely book ship tours, I discovered the Lyvai Tour company in the terminal, and they were offering combined Tchou Tchou train rides, plus unlimited time on the Hop On Hop Off Bus for $50 AUD. I only had to wait a short time, before being squeezed onto the rear carriage of the GREEN Lyvai Tours train. The journey around Noumea takes 1.5 hours, and visits the Notre Dame de Pacific Lookout, Faubourg Blanchet, Ouen Toro Lookout, Cote Blanche, Anse Vata Beach & Lemon Bay Beach. You also go through the Old & the New residential areas.
My tour Guide on the Green Tchou Tchou was "David", and he was brilliant at narrating the history of Noumea. Suggestions for tourists using any of the Tchou Tchou trains ..... try and sit in the front carriage, as the back carriage sways considerably during transit. Secondly, if you want to take photo's, make sure you sit on the very left side of the seat, as most of the attractions are on the left hand side.
This is a very informative tourist treat, and a must do for 1st timers in Noumea.