1. Make a copy of files.txt.... for example: copy files.txt to files.txt.original
  2. Edit files.txt... replace "files.txt" with "files.txt.original"
  3. Make a copy of the file you want to mod... say you want to mod weaponinfo.xml, so you would make a copy of it as weaponinfo.xml.original
  4. Edit files.txt... replace "weaponinfo.xml" with "weaponinfo.xml.original"

So.. step by step... here's what I would do:

1. Make sure you have all the original files (restore from backups if you don't... or worst case scenario reinstall/fix your install).

2. Make sure you can run the game and start/load a game and actually get in game. Don't use the loader if you're using this method.

3. Ensure that your windows is setup to show file extensions (In Explorer... Tools (ALT+T) -> Options -> View... Uncheck Hide extensions for known file types)

4. Ensure that your GTA IV directory/files are not readonly.... this is particularly important if you're on Vista and installed into Program Files -- I've seen some of my files there being write protected. To fix this, right click on the "Grand Theft Auto IV" folder, and click on Properties... uncheck Readonly and then click on OK.

5. Make a backup of pc\files\filelist.pak as filelist.pak.magic and overwrite it with the provided patched filelist.pak (the batch file doesn't do the overwriting with the patched file for you!)

6. Now, try modding one file.... for example, try the common\data\WeaponInfo.xml file. The changes are easily visible, and having a saved game doesn't affect the changes in the file. To mod this we will do the following:

6a. Make a copy of files.txt and call it files.txt.magic. (We're using .magic... but it could be anything you like... just name it differently) Don't ever ever edit any of the .magic files. If you did -- you messed up... start over again.

6b. Go into common\data and make a copy of WeaponInfo.xml and name it as WeaponInfo.xml.magic

6c. Edit common\data\WeaponInfo.xml and make your changes... for an easily visible example, check out opium's change here: http://www.gtaforums.com/index.php?show ... 1058712412

6d. Edit files.txt with notepad...

6e. Find the line saying "common\data\WeaponInfo.xml", and change it to "common\data\WeaponInfo.xml.magic" (no quotes)

6f. Find the line saying "pc\data\filelist.pak", and change it to "pc\data\filelist.pak.magic" (no quotes)

6g. Find the line saying "files.txt" (should be at the very bottom), and change it to "files.txt.magic" (no quotes again)

6h. What you've done now is to point checking part of the game to the WeaponInfo.xml.magic file but the game will still load WeaponInfo.xml when it needs to load the data. Run the game, and test your changes.

6i. If it didn't work at this point... you did something wrong -- don't go any further. If you're happy with the progress and don't mind doing the steps above for each file... don't go any further either!

7. Now that you've proven that it works for one file... you can use the batch file to "automagically" do it for all the files... but before we do, we have to undo the test changes we made in step 5/6. To do this:

7a. Delete common\data\WeaponInfo.xml and rename WeaponInfo.xml.magic to WeaponInfo.xml

7b. Delete files.txt, and rename files.txt.magic to files.txt

7c. Delete pc\data\filelist.pak and rename pc\data\filelist.pak.magic (We do this because the magic.bat will copy filelist.pak to filelist.pak.magic and screw everything up if filelist.pak is already patched before running the magic.bat file)

8. Now extract the magic.bat file to your GTAIV directory. Before you run it, make sure you have admin rights on your computer.

9. If you're on Vista, right click on magic.bat and click on Run as Administrator. Approve any UAC screen you get. If you're on XP, you can just double click on the magic.bat file.

10. When its complete... it has essentially completely done Step 6 for ALL the files mentioned in files.txt (i.e. it just saved you some trouble and some time).

11. Overwrite pc\data\filelist.pak with the provided patched filelist.pak (the batch file doesn't do the overwriting with the patched file for you!)

If you want to be extra safe... make backups of anything you edit (even though the .magic file essentially a backup).