Running unsigned code on the Xbox360 requires a bit of know how and a specific plan tailored to your particular model/chipset. A freshly released hack, however, works on every version of the Xbox.
Dubbed the “Reset Glitch Hack” (it uses a pulse of electricity to disrupt communication with a specific chip on the 360 motherboard during the authentication process thus opening the door for unsigned code and a boot loader) it’s an effective hack for people who aren’t afraid to get their hands dirty. You’ll need to be comfortable soldering, shelling out a small amount of money for the various supplies and microchips you’ll need for the job, and of course no worries about potentially ruining your console with a soldering job gone bad.
The great appeal of the hack, in the face of those things, is that it currently works on every Xbox model out there including the un-JTAGable Xbox 360 Slim. The only downside, risk of damaging your Xbox aside, is that it can take up to 2 minutes to boot since the electric pulse has a 25% chance of disrupting chip communication (and continues to pulse until it gets the timing just right). As a result you’re looking at slightly longer boot times. Not a bad trade off for a works-on-any-machine hack.
Hit up the link below for the step-by-step tutorial. You can also check out the announcement here for a detailed breakdown of how the hack works.