This site belongs to John Whelan who made be contacted via the Trainz forum private messages.
It does not use any scripting. In the downloads area you'll find a few thousand assets both my and some other content creators Trainz assets for various versions of Trainz. Most are version 3.5 or TS12
www.trainz-carriage-wagon-works.com contains screenshots of many of the assets available here
We are listed on www.trainzkuidindex.com which is a database of kuids for Trainz.