Well, I also tried that because I want to have an "undetectable" texture wallhack but ALL *tga files in the folders are just for the UI (User Interface) etc. and not ingame (e.g. Charakter models, walls, weapons,...).
So I wonder why you want to make something "transparent".
1.) Maybe it IS transparent? How u know that your files arnt transparent? If u watch them in some previews by windows they sometimes get a colored background also when they are transparent. The whole UI has a Background so if u turn something transparent it could be that it becomes for example black
2.) Check the file format. Did u save the file as *tga ? Did u activate to save the transparent background? I know from some programs wich fill the transparent area with a color if u doesnt turn some option on/off.
BTW: If u find a way to extract the textures from the models than I would thank u if u show me how
I tried also to filter some sounds in ghostmode... but there arnt the ghost sounds, step sounds and gun-shoot sounds in the folders so I can edit them to hear ghosts better =/.