With this program you can add files to the IMG archives of GTA IV in one click through the context menu of Windows. Convenient, isn't it?
Installation: Unzip the downloaded .zip archive. Run GISF.exe and select your GTA 4 folder. After doing so, right click on any of the files like WAD, WBD, WTD, WFT, WDR, RBS, WDD, WNV, WBN, WPL, SCO, RRR, WBS and CUT. You will see many additional items in the context menu, which will help you throw the file into any GTA 4 archive.