Only way I know how is if you have the game Dead Or Alive 3, beat it in survival mode and get a high score rank. Then it will ask you to enter your name, whatever name you put down will be your XBOX's name.
if youre talking about the name that appears when you start a system link game of Halo, first you have to connect to your box. look in the folder E/UDATA. at the bottom there should be NICKNAME.XBN. use a hex editor like "HDD Hex Editor" (that's what i use b/c its free) and open NICKNAME.XBN. in the top should be your xbox's name. edit it to your liking but be sure to keep the "00" values between letters (those are not periods). once youre done, ftp the file back to your box and overwrite the old one. maybe this will help.
On the back of your XBOX there's an ethernet port, you can use that port to connect your XBOX to your PC. Use a program like FlashFXP on your PC to navigate through your XBOX.
There's an app called xtoolbox that has the function included. If that's not the esiest way,then what is?
