Hi James (or people who know how to use Blender well), I have just started to reliver trains for the Pak128-Britain-Ex pakset and I just want to know. How do you seprate/resize parts on Blender?
Have you followed this tutorial (https://en.wikibooks.org/wiki/Blender_3D%3A_Noob_to_Pro)? You will find it very helpful in understanding the basic operation of Blender.
I think that you may mean this (http://bridgewater-brunel.me.uk/downloads/render_SimutransRender_pak128Britain-65.py) Blender script.
See here (http://lmgtfy.com/?q=how+to+install+a+script+in+blender) for a description of how to find this information.