IMPORTANT NOTE:
For XnView 2.50 (AKA XnView Classic) users, there's no "Viewer" option in the File menu, so the process is different. Here are the steps to follow in that version
1. Open XnView (not necessarily opening one of the .tga files)
2. Go to the Tools menu, and from there click directly on Batch Processing
3. Click Add, navigate to the "Harbinger Part 2 - XnView" directory, select all files in said directory, add them with the Add button, and click OK.
4. Set the output folder to [TSL Directory]\Override, set the output filetype to .tga, and set "Overwrite files" to either "Ask" or "Replace"
5. Click on Go
Edit: And now a question. Both this and your own Telos reskin use CM_Baremetal.txi
Should this be overwritten, or should it be skipped?