Disclaimer: You're using these tools at YOUR OWN risk. It's your own fault if you try to cheat and get banned. Always make sure you back up your files before changing them.

Words to live by: Don't be a jerk or rotten apple. Help your fellow modding community members. Play nice.

MegHalomaniac.exe

This tool is a drag-n-drop style desktop app.

Select which game you're messing with. The default is HaloReach.
Drag-n-drop files:
A. One or more .BIN (game variant) files that are from the selected game (eg, Reach).

B. One or more .GVARXML files.
Pay attention to the "Messages" UI after any of these processes finish for extra details or error info. The log file, MegHalomaniac.log, can also contain additional diagnostic information.

-LordZedd for making the logo.