hi yes, you do need a modchip to install evox onto your x-box, but there are ways to install it using no-mod exploits.
by using exploits i can't really help you out in that area because i have not seen many people do it and don't know much abou it anyway . but visit this link you'll get alot of information about it here. http://www.xbox-scene.com/tutorials.php?t=0,0,1,0,0,0,0,0,0,0,0,0