San Andreas v2.0 Modding
This article explains how to modify the archives of the second version of GTA: San Andreas, based on the work of DexX and jarjar. [1]
Step 3 - Creating the new archive
Now you need to make a new .img file. Now the one down side of IMG Tool 2.0 is you can't create new .img files. So to save time, effort and problems, we will instead be using Alci's IMG Editor 1.5, which is a great tool for this, although sadly is only available on two GTA Modding Websites.
Open Alci's IMG Editor 1.5 (double click the .exe included with the download, Alci's IMG Editor 1.5.exe) and create a new .img file:
http://img371.imageshack.us/img371/5597/step1gu4.jpg
Click File -> New to create a new .img file
Now you need to add whatever files you want to add to the game that would usually be put in the gta3.img file, for example the .dff and .txd file for a vehicle you'd like to replace. In Alci's IMG Editor 1.5 click "Actions -> Import", select the files to add and click "Open" to add them to the file:
http://img138.imageshack.us/img138/9707/step3jg8.jpg
Now import the files into the new .img file
Save it (Ctrl+S) to the models directory in your game's installation directory, call it what ever you called the .img file in Step 1. If it was VEHICLES.IMG, then that's was it needs to be named, if it was something else, then you need to back track, find the name and name it that.