Let me offer this advice. It was invaluable when I learned it. All it took was an email from Sly that helped me use this method. It's 300000x easier than dancing with RW_Tools any other DDS converters. Bee doing it this way for awhile now.
Download this if you don't have Photoshop:
http://www.railsimdownloads.com/files/c ... ceTool.zipDownload this if you have Photoshop and install the ACE plugin:
http://www.railsimdownloads.com/files/c ... lugins.zipNow. I'm not in front of my home computer so I will be using fictitious names. It's simple though.
Let's say you're trying to paint "supertrain" and the texture you want to work on it located
railworks\assets\cooldeveloper\railvehicles\supertrain\repaint1\textures\We'll call the texture "supertrainbody.TgPcDx
Do your normal procedure of using RW_Tools or whatever to export the texture to DDS. Then close those programs, you won't need it anymore until you want to move on and export another texture. ie: Only use it to export to DDS
Ok now.. Paint it, dress it up pretty and save it in ACE format HERE (see bolded below). You will need to create the directory inside the source folder to mirror the foldeer structure that is in the asset folder of this train.. Change no default settings with any ACE saving dialogs that pop up. The only exception is with IHH products I believe. Don't create MipMaps with IHH products.
Railworks\Source\cooldeveloper\railvehicles\supertrain\repaint1\textures\supertrainbody.aceSave the texture EXACTLY the same name as it is really named with the exception of it now being an ACE file.
Open the BLUEPRINT EDITOR (not asset editor)
Expand the folders until you open up all the way to the texture subfolder. ie: \cooldeveloper\railvehicles\supertrain\repaint1\textures\
You should see your newly created ACE file sitting there. Right click,Export.. You're done. It is now automatically converted to TgPcDx and sent over to the
Railworks\assets\cooldeveloper\railvehicles\supertrain\repaint1\textures\ folder and overwrites the supertrainbody.TgPcDx file that is currently there with a newly updated one that you repainted.
Enjoy