http://www.cncgeneralsworld.com/downloads/downloadmanager.asp?action=showPage&page=modding It's the forth download on the list. With FinalBIG you can open up all the .big files in your game directory. (If you installed Zero Hour in the default path, it should be "C:\Program Files\EA Games\Command & Conquer Generals Zero Hour"). But the one were interested in is called "INIZH.big" Open it up & you'll see a list of all the INI files for the game. You'll also notice of slashes "\" in all the names. That means a folder. So in the "Data\INI\Locomotor.ini" the "Locomotor is in a folder called "INI" & that is in a folder called "Data" If you want to modify the speeds of units, modify this INI file. First extract outside the "INIZH.big" file. (It must be in same folers you see in FinalBIG. So when you extract the file, put into the "INI" folder which is in the "Data" folder.)(Sometimes you won't see a folder that you see in FinalBIG, that's no problem, just create new folders for anyone that you don't see in the game directory.)
Now open the "Locomotor.ini" in the "Data\INI" folder & open it up. (It will open in Notepad.) If you want to modify, lets say, Colonel Burton's speed then open up the "Find" program. (ctrl+F) Type in "ColonelBurton" (Caps don't matter.) It should take you to Colonel Burton's locomotor. You might be at his climbing one so be sure. for a start, why don't you just fuss with the numbers. Like change a 20 to 100 & save the file & open up the game & see what happens. If you modified the right number, Colonel Burton will go 5 times faster! Note, this will not allow you to play online because your Colonel Burotn goes faster then everyone elses. To uninstall your modifaction, either rename, move, or delete the Locomotor.ini.
If you want to be a good modify, you'll need to do some exploring because I don't have time to tell you every last detail, but this little tutorial & should help. Try modifying other INI files too. Let me know if you have any problems.