Re: my mustaine livewires won't work.
If you look at the plug at the end of your guitar cable, you will see the tip, then an insulator ring, and then the rest of the shaft (also known as the sleeve). On a stereo plug, or TRS (tip, ring, sleeve), there are two insulation rings so you have the tip, the sleeve shaft at the bottom, but in between those two is the ring (which just so happens to be the section between the two insulation rings).
Stereo Plug:
Now, let's look at the jack.
In this picture, the sleeve lug (btw, a lug is the point where the wire is connected and soldered) is the one at the forefront. The tip lug is the one on top pointing to the right and the ring lug is on the other side. If you remember that the ring is between the tip and sleeve, you'll never mess up, and they go in the same order as the plug TRS does.
EDIT: And no, you do NOT need to use a stereo plug with active pickups, just the jack. See my explanation in an earlier post for the why and how.