Firstly it's good to hear that these scripts work with PS CS2, which you can obtain for free legally (search Google). Whilst not as powerful as some newer versions, I prefer it hugely over GIMP myself. One of the reasons being that PS Actions allow a huge amount of automation to be set up very easily by "recording" commands.
As I said in PM, all you must do is open a US-style RHW texture, select the action you want to run "Euro RHW" and click the play button. It will then process the texture and save it automatically. The output should be a perfect match for the EU-style RHW. Once you've got the hang of that, using the "Automate / Batch" option from the File menu, will allow you to run this script on entire folders in one go too. It's a very powerful tool.
I should point out though, this converts US RHW textures to the new EU standard based on NAM 33. This is not Mandelsoft's texture style, there is no simple way to automate that change. You'd have to literally re-make every missing texture by hand. That's why we changed the EU RHW textures in the first place. Because the only way to continue supporting them was to have a quick/dirty tool such as we do now. That way when new content was added, the US textures are just run through the automated script and we get the EU versions without any large additional workload. It was pretty much that or no EU texture support at all, so very much the best solution.