To obtain TGATool2, download it here: http://www.mnwright.btinternet.co.uk/train/tgatool2.htm
You can reskin any locomotive or item of rollingstock, as far as the Readme will allow you to. But first, you need the following programs:
- TGATool2, as stated above,
- Any paint program, ranging from MS Paint (for simple stuff such as mere renumbering), all the way up to PSP and Photoshop for the more complex, highly detailed stuff, if you were to fully reskin a loco.
The first step is to tell TGATool2 where MakeAce is. MakeAce is a program supplied by MS with MSTS – you need this to export any files to .ace (the format of image used by the game). To do that, go to Prefs Locate MakeAce
Then, browse to the UTILS sub-directory located within your MSTS installation. If you used the default installation path, it should be C

After you’ve located MakeAce, you need to select your default image editing prog. If you wish to save all the *.ace files to *.tga and then load them up manually in your fave prog, this part isn’t needed. However, to keep things simple, now go to Prefs Select Editing Program
As default, this has mspaint.exe in the filename box. You can change this to whatever program you use. For example, if you wish to use PSP, browse to C

After that, go to Prefs Register ACE to TGATool2. This means that whenever you double click on a *.ace file, it automatically loads up in TGATool2.
After this, you are ready to start reskinning! I’ll leave you to figure out how to reskin, and to work out your own personal preferences, just like I have.
To start reskinning, load up the *.ace file in TGATool2, and go to Image Send main image to editor.
This then loads up whatever program you have selected as your image editing prog, and then automatically loads up the texture inside it. Work away to your hearts content, occasionally saving by pressing CTRL+S, until you’ve finished. Note, you can view your work at any time during your reskinning by pressing CTRL+S in your editing prog and going Image Reload Data. Once you’ve finished your reskin, you need to go CTRL+S in your editing prog, and then Image Reload Data in TGATool2.
This then reloads the image in TGATool2, so you are ready to export the *.ace.
If the image has an alpha channel, you’ll need to select Export Ace (Alpha) – Not DXT, and Export Ace for non-alpha channelled textures. DXT is a form of compression.
Browse to where you wish to export it, and click export!
Note: Your firewall may or may not ask you to give makeace.exe permission to access the internet. Give it permission.
That should be all, if you have any further questions the post them below and I’ll try to answer them.