Įditing the 'Gamedata.ini' file can be done with a simple texteditor, set maxcameraheight to something below 1000, 600 or 700 is good usually. If this file is not there you can download it and save it in this location.
The Gamedata.ini file is located in installdirectory\EA Games\Command & Conquer Generals Zero Hour\Data\INI. However this prevents you from playing with people (LAN or online) who haven't changed this value. It is possible, the Gamedata.ini file has a setting called 'maxcameraheight' which allows you to change the camera height.
