To use IMG Tool follow these steps:
First, download it from our downloads database and open it. When it's open, click File and click "Open File", then search for a file called gta3.img in C:/Program Files/Rockstar Games/ Grand Theft Auto Vice City/ models, but ATTENTION: You should get there outside the IMG tool, right click on the Grand Theft Auto Vice City Folder and un-tick "Read Only"!!!
After that, extract the .txd and .dff files to a folder. When you open gta3.img in the IMG Tool, search for the original (with the same names and format) files and delete both. Then go to Tools (or whatever) and click Add, search for the files, select them both and click Open. Then in the same Tools menu, click rebuild (this will take a while, maybe 15 minutes so you'll have to wait.)
Enjoy!