What you'll have to do is make sure you have an xbox 1.0-1.5 and not any higher version. The next thing to do after that is reading up on TSOP flashing which might be kinda tricky on 1.2-1.3 xbox's.
However I would recommend doing a softmod in your case if you can get your hands on whats required.
http://forums.xbox-scene.com/index.php?showtopic=496263 - this one uses your pc and the hotswap method, riskier and harder but can be done if you know what you are doing.
http://forums.xbox-scene.com/index.php?showtopic=430898 - this one however uses a hacked savegame for a few specific games and is a lot easier to handle with the right equipment.