Instructions
Download "DotHalo." It is available from websites like GameFront (see Resources).
Unzip the file and double-click on the "DotHalo" application in the unzipped folder.
Click on "Open Map" on the Map Tools window within the program.
Open your map of choice. Maps can be located in the "Halo 2" directory where you installed the game, or they can be in other folders of your choosing.
Look at the "Tags" window in the program. Find "Biped" on the list.
Click on the "+" next to Biped.
Click on "objects\characters\masterchief\masterchief_mp" from the list. You will get a pop-up window with different options for Master Chief.
Change the "Jump Height," "Standing Height" or "Crouching Height" to whatever value you desire. The default values are listed when the window opens. You can change the values to be higher or lower.
Click back to the "Tags" window and select "Save Changes."
Resign the map using a resign program of your choice, such as "DMR Content Map Resigner."
Drag the map into the "Halo 2" directory.